Compressor Maintenance

If a client expects his refrigeration equipment to perform reliably for many years, preventive maintenance is a necessity.

When equipment constantly breaks down or doesn’t perform to expectations, it’s often because there has never been any preventive maintenance — only emergency service.

Remember, equipment is only as good as the service performed on it.

1) Check oil levels:

Under normal running conditions oil levels should read between 1/2-1/4 way on the sight glass. If you find your compressor is showing no or very little oil on the sight glass and there are no signs of oil leaks, the oil must be somewhere in the system.

Check with manufacturers specifications.

2) Safety controls:

These could become damaged due to vibration or repetitive use, they are a mechanical device and have a limited life, they should be checked at least twice year. Occasionally these switches can nuisance trip, but investigation must be carried out to determine if it is in fact a failed switch or a system problem.

3) Contactors/relays:

Electrical connections throughout the whole system can become damaged, especially where mounted to the compressor terminal plate, over time vibrations can cause loose connections resulting in electric motor failure.

Check the status of the relay contacts. If the relay contacts are pitted, the relay should be replaced, not simply cleaned. Once pitted, the surface will quickly degrade after a clean-up, since the hard coat on the contact has been removed. If they are severely pitted, try to determine if the pitting is due to age, or if the unit is cycling repeatedly for some reason. Safety controls (low pressure, high pressure, case temperature, motor current, or thermostat anticipators) could be causing the short cycling.

If you follow a good preventive maintenance list and haven’t had to change a compressor its good practise to change every 3 years for refrigeration systems and every 5 years for air conditioning systems.

When changing compressor, it is advised that new contactors are always fitted.

4) Condenser/evaporator maintenance:

Poorly performing coils also mean that other parts of the refrigeration/air conditioning system must work harder or for longer resulting in reduced life cycles. With refrigerated/air conditioning systems, compressors must work harder and longer to achieve the required system performance. Poor coil performance in these systems can also lead to other problems that either reduce compressor life or in some circumstances cause catastrophic compressor failure.

They must be cleaned and serviced to help maintain an efficient system and extended compressor life.

5) Crankcase heaters:

A crankcase heater is used to elevate oil temperature to prevent refrigerant migration.

Refrigerant will naturally flow to the coldest part of a system. If a compressor is in a cold environment there is the chance of refrigeration migrating to the crankcase. This can cause a compressor to fail, the oil viscosity dilutes as the refrigerant condenses causing the oils ability to lubricate the compressor. Loss of lubrication will cause the bearings to fail upon start up, seizing the compressor and possibly burning the motor out.

6) Superheat:

A technician should calculate superheat when he or she is analysing the operation of a system problem or on equipment start up.

First, measure it and compare it to the manufacturer’s standards or industry standards, remember the system needs to be at a steady state, meaning it has been operating for at least 10 to 15 minutes, and the case or return air temperature is close to its design value.

This information is to serve as a general guideline. The information contained is not intended to replace manufacturer's information or guidelines. SCREWGLE takes no liability for the information contained. It is SCREWGLE’s implicit intention that nothing contained in this guide replaces any past, present or future warranty policy of SCREWGLE and/or any other manufacturer's equipment.