Problem Solver
High discharge temperatures
The most frequent causes that lead to High discharge temperatures:
- High discharge temperatures
Compressor overheating and the resulting heating of the oil cause the oil to lose its viscosity. When this happens, the oil cannot suitably lubricate the moving parts. The lack of lubrication causes specific elements, such as the bearings, to excessively overheat and to wear out quickly, and cause the oil to carbonise.
Among the most common causes are a high value of the compression ratio and a low refrigerant load. These phenomena cause a low flow of refrigerant. Since the heat from the motor and from the friction caused by a compressor are always present, any phenomenon that reduces the flow of refrigerant gas, to a level outside the limits, will lead to the compressor not being cooled enough, causing consequent high discharge temperatures.
Oil loses viscosity at temperatures between 85º C and 95º C, which causes the protective film to be eliminated and the consequent metal-metal contact, which will cause the compressor to mechanically fail.
The discharge temperature cannot be higher than 125º C, as it can be damaging to the oil.
A high compression ratio is generally attributed to problems with the condenser or evaporator, inadequate system control or a combination of all three.
To rectify the problem, we recommend verifying that the condenser and evaporator are clean, checking the air or water flow and temperature from the condenser and evaporator.
A low refrigerant load is characterised by the presence of gas bubbles in the liquid line glass sight, due to the low intake pressure and greatly overheated gas.
To rectify the problem, you must add refrigerant to the system, after first determining why refrigerant is being loss.
Ineffective system lubrication
The most frequent causes that lead to Ineffective system lubrication:
- Oil dilution
This is the most common problem, owing to the great affinity it has with the refrigerant.
The oil may become too diluted owing to the refrigerant during prolonged stop, making it lose part of its lubricating qualities.
Depending on the type of oil, the oil-refrigerant blend can also become saturated, causing the two fluids to separate. The denser blend, rich in refrigerant, will go to the bottom of the housing, while the less dense and oil-rich blend will remain on the top.
When a compressor is started up with too much refrigerant in the housing, the refrigerant-rich blend is suctioned by the oil pump. As it is an excellent solvent, the refrigerant removes the oil film on the two bearings.
Furthermore, highly-diluted oil produces a foam that makes the pump lose its pumping ability. All of this causes serious damage to the bearings, crankshaft and piston-connecting rod set.
These phenomena happen because the compressor is the last element to cool after a stop and is also the last to heat up as the temperature of the system rises. Therefore, the compressor is the coldest part of the system after several hours of the equipment being turned off. The emigrating refrigerant will gather and condense in the bottom of the compressor, causing the oil to dilute, due to affinity between them.
To prevent dilution, we advise using a heating element in the compressor housing, as this will reduce the oil-refrigerant affinity and therefore prevent the migration of the compressor liquid. It is important for the resistance is heating the housing oil, primarily during prolonged stops. - Loss of oil
Losing oil is very damaging for the crankshaft and other moving parts, since they cannot sufficiently cool and excessive heat is generated.
Some of the most common causes for this loss are: too short of cycles, too much oil foaming and long periods with minimum loads, accompanied by incorrect pipe sizes.
During short-cycle periods, the compressor can pump oil for inside the system at a higher percentage than is being returned. The result is obtaining a reduced level of oil.
When the oil foams inside of the housing, it will be carried by the refrigerant gas and compressed inside the system. If foaming persists, the oil level may drop. Foaming may be due to oil dilution or due to using unsuitable oil.
Liquid hammering
The most frequent causes that lead to Liquid hammering:
- Return of refrigerant liquid to the compressor due to an incorrect expansion valve, a damaged evaporator fan or obstructed air filters
An oversized expansion valve or one that operates poorly –in the case of a failure of evaporator fan (incorrect air distribution in the battery) or obstructed air filters– can cause a return of liquid as a consequence of liquid hammering.
This will happen when the refrigerant liquid exceeds the evaporator capacity and returns through the compressor intake line, as liquid more than as steam.
During the operating cycle, liquid flooding the compressor may cause wear to moving parts due to the dilution effect to the oil and the loss of oil in the compressor. During the stop cycle, the migration of refrigerant to the compressor can happen very quickly, giving rise to a liquid hammering when turned on. - Migration of refrigerant
This is the term used to describe the accrual of refrigerant liquid in the coldest part of the system or, in other words, the refrigerant condenses in the coldest part of the system. Generally, this part tends to be the compressor when outside temperatures are too low or when they are too high, although this may also happen in the evaporator.
Migration occurs mainly when the compressor is at a physically lower level than the evaporator or condenser.
To prevent the migration of refrigerant liquid coming from the condenser, we advise installing a retention valve on the compressor discharge line. It is also advisable to install a U-bend at the condenser inlet.
With respect to evaporators, we advise stopping the compressor for liquid collection. We also recommend installing a U-bend right at the outlet of the evaporator.
Without these precautions, it is very likely that large quantities of refrigerant liquid return through the compressor’s intake or discharge line, causing a liquid hammering and the dilution of the oil.
We advise have a heating element in the compressor housing. Although it does not guarantee avoiding this phenomenon, as depending upon the quantity of refrigerant, the capacity of the heating element may be surpassed. - Oil return
The return of oil is just as damaging as the return of refrigerant liquid. It normally happens when the pipes are not properly designed and, as a consequence, there will not be uniform movement of the oil throughout the installation, causing an accrual of oil hammering.
This excess oil leads to a significant reduction in the system’s cooling ability, as the heat exchange capacity in the evaporator is drastically reduced.
Take special precaution for systems with more than one compressor in parallel or in tandem.
Return of liquid
The most frequent causes that lead to Return of liquid:
- Return of liquid
The return of liquid is mainly caused when the gas overheats in the compressor intake moves towards 0 K, owing to the detergent effect of the refrigerant, which can remove all the lubrication film from the compressor’s moving parts. This phenomenon will cause these parts to break.
When the compressor undergoes a return of liquid, we can see how the parts of the compressor end up clean, namely, without any trace of oil and no signs of carbonisation.
System contamination
The most frequent causes that lead to System contamination:
- Rust
It frequently appears in maintenance operations such as oil changes. Oil has oxidising characteristics that, with the combination of oil and water, can cause oxidation and rust.
Rust also forms in pipes when heat is applied during welding in the presence of air. This can be prevented by decompressing the air inside the pipe with inert gas, such as dry nitrogen, before applying heat.
Rusting can be removed by installing an intake filter before the compressor, which will retain these elements, thus preventing their entry into the compressor. After start up, we advise changing this filter again. - Copper plating
This happens in 2 phases:
In the first, the copper dissolves in the by-products from an oil-refrigerant reaction. The quantity of copper dissolved is determined by the nature of the oil, by the temperature and by the presence of impurities. In the second phase, the dissolved copper is deposited into the metal parts in an electro-chemical reaction.
High temperatures are the factor that most heightens this problem. A second factor in the formation of copper coating is the use of improper oil. Specific oils react more easily with refrigerants than others, under the effect of high temperatures, causing the copper to dissolve.
Finally, the presence of air or humidity and other contaminants accelerate the movement of copper into the parts such as the valve plates, oil pump and crankshaft.
To prevent these types of problems, we advise always using the type of oil recommended by the manufacturer, analysing and correcting the causes of high temperatures and evacuating the system as many times as necessary to ensure that all air and humidity are removed. We also advise using a filter drier with a high moisture absorption power. - Humidity
The presence of humidity in the system, whether in air or water, can lead to other contamination owing to the formation of oxidation, rust and decomposition of the refrigerant.
Excessive heat from friction, copper coating and worn-out surfaces can be related to this contaminant.
The main source of contamination from humidity is the air that enters the system when the pipes are being installed. Another way that humidity may enter is through unsuitably handled and used oils as replacements for the original compressor oil.
Without suitable evacuation and dehydration methods for the refrigerant system, a small quantity of water or air can induce rust and accelerate the process of the formation of other types of contamination.
Humidity can be detected by analysing the oil or using a liquid sight glass in the liquid line.
The safest way to remove humidity is to conduct a good evacuation, followed by a vacuum breaker. We recommend doing this process a couple times using dry nitrogen. - Dirtiness
Foreign materials, such as dirt, welding flux and chemical products, in combination with the air, cause chemical imbalances that cause the oil molecules to break. Along with high system discharge and friction temperatures, this can result in the formation of acids, sludge or a combination of both.
Burnout located
The most frequent causes that lead to Burnout located:
- Burnout located
When there is a mechanical breakage, some of the metal parts may be housed in the winding mechanisms, causing damages to the insulation of the motor. This loss of insulation can cause a short circuit between the poles. The heat from this short circuit can burn out the insulation in the surrounding poles, which can end up causing a phase or a phase-earth short circuit.
A burn at a specific point can also be caused by strain to the motor.
Complete burn
The most frequent causes that lead to Complete burn:
- Complete burn
Occurs, for example, when one of the phases is out of phase.
When the motor is stopped is when there are greater chances that the motor will burn out completely. This is because when it is energised, electric and physical demands on the coils are greater. If the voltage is low or the compressor is mechanically blocked at this moment, the compressor will burn out if the motor protector does not act in a very short period of time.
Another of the most common causes is inadequate cooling of the motor due to a low flow of intake gases.
In short cycles, the motor can also overheat. Frequent powering up, with the consequent current peaks, and a reduced flow of intake gases cause the motor to overheat, which can end up burning out the motor.
To prevent this from happening, we recommend that you install some type of timing device to limit how often the compressor powers up.
Electric failures caused by mechanical problems
The most frequent causes that lead to Electric failures caused by mechanical problems:
- Electric failures caused by mechanical problems
Motor overrun is one of the most common causes when there are mechanical problems in the compressor.
Wear to bearings can lead to a runout between the rotor and stator. Because the space between them is very small, this runout makes the rotor damage the stator laminations, causing a failure in the slot insulation, which will in turn cause a phase-earth short circuit.
Worn-out bearings are the main cause of motor overrun. This can occur due to dilution of oil or by some type of contamination of the oil.
Oil that contains suspended particles can reach the motor through the intake pipes, causing damage to them.
Lack of phases
The most frequent causes that lead to Lack of phases:
- Lack of phase
In a three-phase motor, a lack of current can cause it to perform like a single-phase motor. This means that the other 2 phases work with too much current. If there is no protector to turn off the motor, the 2 phases will burn out quickly.
Or one of the phases could overheat before the other one, so that one of them does not burn out.
Wiring done wrong
The most frequent causes that lead to Wiring done wrong:
- Wiring errors (single phase motors)
Wiring errors in single-phase motors are quite common. This happens by connecting the auxiliary phase as the main one or incorrectly connecting the electric components.
- Banging noises in compressor
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Liquid ‘hammering’ in the cylinder due to the entry of liquid refrigerant in compressor.
Reset the expansion valve (less overheating).
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Boiling oil due to the absorption of liquid refrigerant into the oil.
Install heating element in the compressor housing.
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Wear of moving parts of the compressor.
Repair or change the compressor.
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Liquid ‘hammering’ in the cylinder due to the entry of liquid refrigerant in compressor.
- Brown liquid in sight glass
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Impurities in the form of small particles in the installation.
Change the liquid level glass and filter drier, clean everything.
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Impurities in the form of small particles in the installation.
- Chamber temperature too high
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Small compressor capacity.
Change the compressor for a larger one.
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Workload of the chamber too large due to:
- a) input of products that are not cold.
Recommend inserting the products when they are cold, putting in less quantity or redesigning the installation.
- b) Great internal energy consumption (lighting, fans).
Try to attain lower consumption by using more efficient elements, or redesigning the installation.
- c) Chamber poorly insulated.
Improve insulation in the chamber.
- d) Air infiltration.
Make the chamber more hermetic and minimise opening the door.
- a) input of products that are not cold.
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Evaporator too small.
Change the evaporator for a larger one.
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Flow of coolant to the evaporator very small or non-inexistent.
See "Steam bubbles in the sight glass".
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Evaporation pressure regulator set to a cut-off pressure that is too high.
Adjust the pressure regulator using the pressure gauge to assist you.
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Low pressure switch set to a cut-off pressure that is too high.
Adjust the pressure switch to the correct cut-off pressure, using the pressure gauge to assist you.
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Capacity control valve is opened to an evaporation pressure that is too high.
Adjust valve to a lower opening pressure.
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Intake pressure control valve adjusted to an opening pressure that is too low.
Adjust intake pressure valve to a higher opening pressure, provided that the compressor accepts this operation.
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Small compressor capacity.
- Chamber temperature too low
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Failure of thermostat in chamber or cut-off temperature set to a value that is too low.
Adjust the thermostat or change it.
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Failure of thermostat in chamber or cut-off temperature set to a value that is too low.
- Compressor doesn’t start
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No voltage reaches the compressor
Contact the electric company.
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Defective electric control gear (single-phase compressors)
Locate the defective item and replace it.
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Melted fuses
Locate the failure and change the fuse.
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General switch turned off
Change the position of the switch.
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Thermostatic protective action for the motor due to:
- a) Condensation pressure too high
- b) Intake pressure too high.
- c) power supply voltage is too low.
Contact the electric company.
- d) a phase is missing.
Locate failure and repair it.
- e) short circuit in motor windings.
Change the compressor and thoroughly clean the system using a new filter drier.
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Protectors on motor windings open due to excess energy consumption.
Wait until the coils are cool enough and then start up the system again.
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Motor start-up contacts burned out due to:
- a) startup current is too high.
Locate the cause of the motor overload, repair it and change the contactor.
- b) contactor is too small.
Change the contactor for a larger one.
- a) startup current is too high.
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Motor windings burned due to:
- a) overload.
Locate and repair the cause of the overload, and change the motor or compressor.
- b) formation of acids (except in open compressors).
Locate and repair the cause of acid formation, change the motor or compressor, thoroughly clean the system, install a new filter drier.
- c) motor is too small.
Change the compressor for a larger one and change the motor in the case of open compressors.
- a) overload.
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Bearings and cylinders seized up because:
- a) there is not enough or no lubrication.
See ‘Lack of lubrication’.
- b) there is dirtiness in the system.
Clean the system and install a new filter drier and replace the compressor.
- c) of copper coating on smooth parts due to the formation of acids.
Clean the system and install a new filter drier and replace the compressor.
- a) there is not enough or no lubrication.
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No voltage reaches the compressor
- Compressor too hot
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Compressor overload due to an excessive load in the evaporator.
Reduce load in the evaporator or replace it with a larger one.
- Motor and cylinders not cooling properly due to:
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Condensation pressure too high
See "Condensation pressure too high".
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Compressor overload due to an excessive load in the evaporator.
- Condensation pressure too high
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Air or gasses not condensable at the installation.
Purge the condenser.
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Condenser surface area is too small.
Change the condenser for a larger one.
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Accumulation of refrigerant in the condenser due to it being overloaded.
Remove part of the refrigerant until you have obtained normal condensation pressure.
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Regulation of condensation pressure is incorrect (too high).
Regulate to the correct pressure.
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In air condensers:
- a) condenser surface dirty.
Clean the condenser.
- b) fan or blades defective or too small.
Exchange them.
- c) access restricted or difficult of air to the condenser.
Locate possible impediments or change the compressor location.
- d) room temperature is too high.
Change the location of the condenser to a site that is not as hot, providing a source of fresh air.
- e) inverse air flow through the condenser.
Change the fan rotation direction.
- a) condenser surface dirty.
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In water condensers:
- a) water temperature is too high.
Try to lower the water temperature.
- b) water flow is too small.
Increase the flow of water.
- c) dirtiness inside the pipes.
Clean the pipes.
- a) water temperature is too high.
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Air or gasses not condensable at the installation.
- Condensation pressure too low
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Condenser surface area is too big.
Change the condenser for a smaller one or install a pressure regulator.
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Low evaporator charge.
Establish control for the condensation pressure.
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Intake pressure is too low, due to the lack of liquid in the evaporator.
Locate the failure between the condenser section and the expansion valve.
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Leaks in the discharge and intake valves (valve plate).
Change valve plate or compressor.
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Regulation of condensation pressure is incorrect (too low).
Regulate to the correct pressure.
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Liquid recipient is located in a site that is too cold with respect to the condenser and without insulation.
Insulate the recipient or place it in a hotter location.
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In air condensers:
- a) air temperature is too high.
Establish control for the condensation pressure.
- b) air flow is too great.
Establish a speed control in the fan motor or exchange it for a smaller one.
- a) air temperature is too high.
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In water condensers:
- a) water temperature is too low.
Provisionally reduce water flow through an automatic water valve.
- b) water flow is too great.
Install an automatic water valve.
- a) water temperature is too low.
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Condenser surface area is too big.
- Discoloured oil
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Installation polluted due to:
- a) insufficient cleaning after assembly.
Change oil and filter and clean the entire circuit, if necessary.
- b) decomposition of oil due to moisture at the installation.
Change oil and filter and clean the entire circuit, if necessary.
- c) decomposition of oil due to high discharge temperatures.
- d) remains of particles due to wear of the moving components.
Change damaged components or the compressor, clean circuit and change oil and filter.
- e) insufficient cleaning after the electric motor has burned out.
Install an intake filter and change it as many times as necessary, after a thorough cleaning.
- a) insufficient cleaning after assembly.
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Installation polluted due to:
- Faded yellow liquid in sight glass
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Moisture in the installation due to possible leaks.
Locate leaks if there is one, verifying that there are no acids in the installation. Change the filter several times. Change oil and refrigerant if necessary.
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Moisture in the installation due to possible leaks.
- Frost in the evaporator (air cooled)
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Defrosting operation not done correctly or not done at all.
Establish a defrosting system or adjust the existing one.
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Too much moisture in the cooling chamber due to the entry of moisture from:
- a) products that are not packed.
Package the products or adjust the defrosting operation.
- b) entry of air into the cooling chamber through door or grilles.
Cover the grills, avoid opening the door unnecessarily and check that the panel assembly is correct.
- a) products that are not packed.
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Defrosting operation not done correctly or not done at all.
- Frost in the intake line
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The expansion valve is open too much.
Adjust the pressure.
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Lack of insulation in the intake pipe.
Insulate the pipes, because if the pipes are not well insulated in low-temperature applications, they sweat.
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Maladjusted temperature control.
Regulate its stoppage.
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The thermostat bulb does not have a good contact.
Ascertain that there is good contact with the evaporator tube.
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The expansion valve is open too much.
- Humidity too low inside chamber
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Chamber poorly insulated.
Improve insulation in the chamber.
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Great internal energy consumption (lighting, fans).
Try to attain lower consumption by using more efficient elements.
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Small evaporator operating at low evaporation temperature.
Change the evaporator for a larger one.
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Chamber poorly insulated.
- Installation output lower than its potential
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Partial obstruction of one of the components in the liquid line.
Locate the component and clean it, exchanging it if necessary.
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Breakdown in the expansion valve (hole too small, reheating too high, loss of charge at the valve, partial obstruction...).
Find out the cause and repair it or change the expansion valve if necessary.
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Partial obstruction of one of the components in the liquid line.
- Intake gas temperature too high
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Little feeding of refrigerant to the evaporator, due to:
- a) small load of refrigerant in the overall system.
Load to the suitable level.
- b) Failure in the liquid line or one of its components.
Locate the component and clean it, exchanging it if necessary.
- c) expansion valve adjusted with an reheating value that is too high or partial loss of the bulb charge.
Reset the expansion valve or change it if necessary.
- a) small load of refrigerant in the overall system.
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Little feeding of refrigerant to the evaporator, due to:
- Intake gas temperature too low
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Too much feeding of refrigerant to the evaporator, due to:
- a) expansion valve adjusted with an reheat value that is too low.
Reset the expansion valve.
- b) expansion valve bulb placed in a site that is too hot or with poor contact with the line.
Change the position of the bulb or position it correctly.
- a) expansion valve adjusted with an reheat value that is too low.
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Too much feeding of refrigerant to the evaporator, due to:
- Intake pressure too high
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The compressor is too small.
Change the compressor for a larger one.
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Installation is overcharged.
Less load, change the compressor for a larger one, install an intake pressure valve.
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Defective capacity regulation.
Exchange or adjust the capacity regulator.
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Defective valve plates.
Change the valve plates or change the compressor, if you have an hermetic one.
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The compressor is too small.
- Intake pressure too high and low intake gas temperature
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Reheating too low or bulb in bad position.
Reset the overheating, changing the position bulb.
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Hole of the expansion valve is too big.
Change the hole for a smaller one.
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Reheating too low or bulb in bad position.
- Intake pressure too low
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Too little load at the installation (few products to cool).
Install a semi-hermetic compressor capacity regulator, increase the differential pressure of the low pressure switch.
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Lack of liquid refrigerant in the evaporator due to:
- a) lack of liquid refrigerant in the recipient.
- b) the liquid line is too long or too narrow or with curves that are too pronounced.
Find out the cause and fix it.
- c) drier filter is partially obstructed.
Clean or change the filter if necessary.
- d) solenoid valve strained.
Change the solenoid valve.
- e) lack of liquid sub-cooling.
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Evaporator too small.
Change evaporator for a larger one.
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Defective evaporator fan.
Change evaporator fan.
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Large drop in pressure in the evaporator and/or intake line.
If necessary, change the evaporator or intake line.
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The defrosting operation was not done.
Establish a defrosting system.
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Accumulation of oil in the evaporator.
See "Oil level too low in the compressor housing".
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Too little load at the installation (few products to cool).
- Level of liquid in recipient too high
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Too much liquid loaded into the installation.
Remove a suitable load of refrigerant so that condensation pressure continues to be adequate and no steam bubbles are produced in the compressor sight glass.
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Too much liquid loaded into the installation.
- Level of liquid in recipient too low
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Lack of refrigerant in the installation.
Check for possible causes (leaks, evaporator overload), repairing the failure and reloading the installation.
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Overcharged evaporator.
- a) too little charge leads to the refrigerant accruing in the evaporator.
Adjust the expansion valve.
- b) failure in the expansion valve.
Change the expansion valve.
- a) too little charge leads to the refrigerant accruing in the evaporator.
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Accumulation of liquid in the condenser, due to pressure differences (the condenser pressure is lower than the recipient pressure).
Place the recipient next to the condenser.
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Lack of refrigerant in the installation.
- Oil boiling during operation
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Liquid refrigerant moving from the evaporator to the compressor crankcase.
Reset the expansion valve (maximum overheating).
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The floating valve does not completely close (installations with oil separator).
Change the float valve or separator, if necessary.
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Liquid refrigerant moving from the evaporator to the compressor crankcase.
- Oil boiling when turned on
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Absorption of liquid refrigerant in the crankcase oil due to room temperature that is too low.
Install heating element in the compressor housing.
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Too much absorption of liquid refrigerant in the separator oil during stops because the oil separator is too cold (for installations with oil separators).
Install heating elements that are thermostat controlled or install a delayed-effect solenoid valve on the oil return line.
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Absorption of liquid refrigerant in the crankcase oil due to room temperature that is too low.
- Oil level excessively high in the compressor housing
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Too much oil.
Empty the housing to the correct level, first ensuring that it is not due to absorbing liquid refrigerant.
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Return of oil from the evaporator is bad at low charges.
Properly dimension the intake pipes, if necessary using oil traps and lifts.
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Absorption of liquid refrigerant in the crankcase oil due to room temperature that is too low during prolonged stoppages.
Install heating element in the compressor housing.
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Too much oil.
- Oil level excessively low in the compressor housing
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Too little oil.
Load oil to the correct level, first ensuring that the lack of oil is not due to it accruing in the evaporator.
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Bad return of the oil from the evaporator due to:
- a) vertical intake pipes have a diameter that is too large.
Resize pipes and install oil traps in the vertical sections.
- b) The absence of an oil separator when the condenser or evaporator is above the compressor.
Install an oil separator.
- c) the horizontal intake line should have an inclination.
Calculate the slopes necessary.
- a) vertical intake pipes have a diameter that is too large.
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Wear of piston rings and piston cylinder.
Change the worn out components or compressor.
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In compressors connected in parallel (with regulation of oil level):
- a) floating valve partially or totally plugged.
Clean or exchange the level casing and the float valve.
- b) floating valve strained.
Clean or exchange the level casing and the float valve.
- c) electronic oil level indicator not connected correctly.
Check the connections.
- a) floating valve partially or totally plugged.
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In compressors connected in tandem (with oil equalisation line):
- a) the compressors are not on the same horizontal plane.
Make the compressors level so that both of them are on the same plane.
- b) the equalisation line has a diameter that is too small.
Install an equalisation line with a larger diameter.
- a) the compressors are not on the same horizontal plane.
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Too little oil.
- Steam bubbles in the sight glass in front of the expansion valve
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Lack of sub-cooling due to a drop in pressure that is too great in the liquid line due to:
- a) length of the liquid line is too extreme with respect to its diameter.
Change the diameter of the liquid line for another more suitable one.
- b) the diameter of the liquid line is too small.
Change the diameter of the liquid line for another more suitable one.
- c) partial or total obstruction of the filter.
Check if there are any impurities in the installation, cleaning and changing the filter if necessary.
- d) failure in the solenoid valve.
Replace the solenoid valve.
- e) curves are too pronounced in the liquid line.
Change the pronounced curves that could cause a large drop in the pressure.
- a) length of the liquid line is too extreme with respect to its diameter.
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Lack of liquid sub-cooling due to high temperatures close to the system that penetrate the liquid line and leading to said insufficient sub-cooling.
Reduce the room temperature or install a heat exchanger between the liquid and intake line, insulate the pipes on the liquid and intake lines.
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Condensation pressure too low
See "Condensation pressure too low".
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Lack of liquid in the installation.
Reload the installation, but you must make sure that the other causes listed are not present, as this could cause the system to overload.
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Too high of a drop of hydrostatic pressure in the liquid line (too great of a difference between the thermostatic valve and the recipient).
Install a heat exchanger between the liquid and intake lines if liquid is rising.
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Lack of liquid in the installation.
Reload the installation, but you must make sure that the other causes listed are not present, as this could cause the system to overload.
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Lack of sub-cooling due to a drop in pressure that is too great in the liquid line due to:
- Temperature at discharge line too high
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Intake pressure is too low, due to:
- a) lack of liquid in the evaporator.
Locate the failure in the section between the recipient and the intake line.
- b) evaporator charge is too low.
- c) leaks in the discharge and intake valves (valve plate).
Change valve plate or compressor.
- d) excessive reheating in the heat exchanger or in the intake storage battery.
Do without the heat exchanger or select a smaller one.
- a) lack of liquid in the evaporator.
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Condensation pressure too high.
See "Condensation pressure too high"
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Intake pressure is too low, due to:
- Temperature at discharge line too low
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Movement of liquid refrigerant to the compressor (expansion valve adjusted to reheating that is too low or bulb in bad position).
Reset the valve, or put the bulb back in.
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Condensation pressure too low
See "Condensation pressure too low"
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Movement of liquid refrigerant to the compressor (expansion valve adjusted to reheating that is too low or bulb in bad position).
- The compressor cools down, but doesn’t stop or runs too long
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Thermostat and pressure switch are poorly regulated or defective.
Adjust them to normal values or replace them.
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Thermostat bulb in incorrect position.
Ascertain that there is good contact with the evaporator tube.
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The refrigerant is not circulating adequately because:
- a) the liquid valve is partially closed.
Open the liquid valve.
- b) the liquid filter or drier is obstructed.
Clean filters or replace them.
- c) the liquid line is obstructed.
Remove the obstruction or change the liquid line.
- d) the diameter of the liquid line is too small.
Change it for one with a larger diameter.
- e) it needs refrigerant.
Locate the leak and remove it, add refrigerant.
- f) the expansion valve is open too much.
Adjust the valve.
- g) the expansion valve is installed in a site that is too cold.
Change the location of the valve.
- a) the liquid valve is partially closed.
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The equipment is working overloaded because:
- a) of the entry of articles that are not cooled down.
Recommend that the article is input cold.
- b) the doors are continuously open.
Recommend that the door is open as little time as possible.
- c) there is insufficient insulation.
Improve the insulation.
- d) the compressor and/or evaporator are too small.
Change them for larger ones.
- a) of the entry of articles that are not cooled down.
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Thermostat and pressure switch are poorly regulated or defective.
- The compressor doesn’t stop and doesn’t cool down much
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The amount of refrigerant circulating is not enough because:
- a) the liquid valve is partially closed.
Open the liquid valve.
- b) the liquid filter or drier is obstructed.
Clean filters or replace them.
- c) the liquid line is obstructed.
Remove the obstruction or change the liquid line.
- d) the diameter of the liquid line is too small.
Change the diameter to a larger one.
- e) the intake line is partially obstructed.
Remove the obstruction or change the intake line.
- f) the intake line is too small.
Change the diameter to a larger one.
- g) refrigerant needs to be added.
Locate the leak and remove it, add refrigerant.
- h) the expansion valve is partially obstructed.
Clean valve, install filter drier.
- i) the expansion valve is damaged or poorly adjusted.
Replace the valve or adjust it.
- j) The expansion valve bulb is partially discharged.
Change the expansion valve.
- k) the expansion valve is installed in a site that is too cold.
Change the location of the expansion valve.
- a) the liquid valve is partially closed.
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Compressor inefficient because:
- a) there are valves or segments that leak.
Repair or change the compressor if using an hermetic one.
- b) the compressor is too small.
Change it for a larger one.
- a) there are valves or segments that leak.
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Compressor overloaded because:
- a) goods are input that are hot or at greater quantities than admitted.
Recommend that the product is input cold or adjust the amount.
- b) the doors are continuously open.
Advise to keep openings to a minimum.
- c) there is insufficient insulation.
Improve the insulation.
- d) the compressor and/or evaporator are too small.
Change them for larger ones.
- e) the circulation of air inside the chamber is defective.
Place the article so that it does not impede air from circulating.
- a) goods are input that are hot or at greater quantities than admitted.
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Compressor operating at low speed.
Check the voltage.
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The evaporator isn’t working correctly because:
- a) there is too much frost on the battery.
Defrost.
- b) there is an accumulation of oil on the coil.
Check if there is an obstruction and dismantle it to extract the oil.
- a) there is too much frost on the battery.
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The amount of refrigerant circulating is not enough because:
- The compressor has short cycles
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Control differential very tight, due to being poorly or wrongly adjusted.
Increase the differential or replace it if it is defective.
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Expansion valve fails for one of the following reasons:
- a) ice, wax, dirtiness causing the expansion valve or filter to partially close.
Clean valve and filter.
- b) small hole.
Exchange it for a larger size.
- c) bulb discharged.
Change the expansion valve.
- d) valve installed in a site that is too cold.
Change the location of the expansion valve.
- a) ice, wax, dirtiness causing the expansion valve or filter to partially close.
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The motor overload mechanism is triggered due to:
- a) low voltage.
Less load, increase section.
- b) small motor.
Replace it with a larger one.
- c) worn out or poorly lubricated bearings.
Replace or lubricate.
- d) earthed or short circuit.
Repair or change it.
- a) low voltage.
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Obstruction in the liquid or intake line, due to:
- a) small liquid line or too much elevation towards the evaporator.
Change for a larger one or install a heat exchanger.
- b) the liquid filter or drier is obstructed.
Clean filters or replace them.
- c) the liquid or intake line is partially obstructed.
Remove the obstruction.
- d) the intake line is too small.
Change the diameter to a larger one.
- e) the liquid valve is partially closed.
Open the liquid valve.
- f) it needs refrigerant.
Locate the leak and remove it, add refrigerant.
- a) small liquid line or too much elevation towards the evaporator.
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The intake pressure is too low for a small evaporator.
Change it for a larger one.
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Control differential very tight, due to being poorly or wrongly adjusted.