WHY REFRIGERATION SYSTEMS FAIL:
THIS COULD BE DUE TO A NUMBER OF ISSUES. ONE THING THAT ALL THE EXAMPLES BELOW HAVE IN COMMON IS COMPRESSOR FAILURE!
Typical compressor failure by type:
Scroll type compressor: A classic compressor failure scenario is when the liquid refrigerant washes the oil from the sump and this causes bearing seizure thus causing the compressor to burn out, we call this down to earth. It is imperative to have your equipment commissioned by a professional after it has been installed and after any major repairs, this will ensure the correct rotation and superheat adjustments have been made.
Piston type compressor: Liquid is a big problem because a piston compressor cannot compress liquid. Liquid causes the valve plates to smash, damage the pistons and snap the con rods. We have seen compressors with pistons missing due to liquid flooding!
Acid in the refrigerant system:
This can be caused by a previous compressor burn out or moisture that has been introduced by a poor repair job or by an inexperienced engineer not connecting his or her gauges correctly. If the engineer connects the gauges (usually during a service) and does not purge the air out of the gauge lines this can introduce moisture into the system. This will turn the refrigerant into an acidic cocktail and erode the copper windings on the motor within the compressor and cause it to go down to earth. When I say down to earth, I mean it strips the copper on the windings in the motor, then the oil becomes a conductor and electricity shorts out on the compressor body which is bolted to earth.
How to prevent liquid flooding
Check the flow rate of the water or other medium across the evaporator and adjust the expansion valve accordingly. The expansion valve controls the amount of liquid refrigerant passing through the evaporator. If there is too little the chiller will not perform as well as it should and cause the compressor to over heat, too much will cause liquid to flood back to the compressor and wash oil out.
Faulty electrical components and poor maintenance:
If the compressor contactors are not inspected you will find that a 3 phase motor will burn out very quickly if its only getting 2 phases. The contacts inside a contactor have a useful life span, this has to be respected if you want your motors to last and is often over looked by many engineers.
Failures due to a blocked condenser:
This causes the compressor to run at very high pressures causing the motor to run hard. If you were to run your car at full capacity for long periods you would not expect it to last would you? Even though a condenser looks clean it might not be, just look and see if you can see day light through it, if not blow it through with compressed air, compressed nitrogen or pressure wash it.
These are some of reasons for compressor failure but not all, regular maintenance and adjustments will prolong the life of your equipment and will save you money on energy bills.
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