Bert teaches a class about failed compressors and what you should do when you encounter one; he also explains why you don't want to "just replace it."
Acid can kill a compressor, and it is one of the most common causes of compressor death after replacement. Moisture contamination in the system mixes with POE oil to form acid, which degrades the oil's ability to lubricate the compressor and leads to premature failure. High heat and electrical burnout may also cause acid formation in the system.
When you diagnose a compressor, you will want to follow an extensive diagnostic process, not just replace it. A thorough diagnosis will help you figure out if the system has acid. Some common signs of acid in the system include positive results on an acid test kit and a pungent odor when you remove your hoses.
When addressing an acid problem, you will want to replace the compressor AND accumulator, do an acid flush or other form of acid treatment, and install a suction line filter drier (being mindful of the one-way flow and appropriate installation practices). You can either remove the contaminated line drier after 10-14 days or replace it with a fresh one after 10-14 days.
Be mindful of system and condenser airflow when you diagnose a compressor; watch for inappropriate or multiple filters, damaged or improper ductwork, inappropriate blower settings, a dirty or clogged evaporator coil, a dirty blower wheel, or a dirty and impacted condenser. Poor airflow can cause high temperatures and pressures, which strain the compressor. Airflow issues at the evaporator can also prevent refrigerant from fully boiling off, which can lead to liquid going into the compressor and causing premature failure. It is important that you quote for these issues so that customers can make educated decisions.
You'll also want to be mindful of the refrigerant charge and how it may contribute to early compressor failure. Low refrigerant charge can cause the superheat to be higher than usual; coupled with longer runtimes, a low refrigerant charge can be a problem when we're dealing with refrigerant-cooled compressors. We can use a P-T chart, do a standing pressure test, or weigh out the refrigerant to check for a low refrigerant charge. Leak detection can help you find a leak, which is a common cause of low refrigerant charge. It's also a good idea to be prepared to complete a full test after installing and starting up the new compressor.
Electronic issues may also be involved in compressor failure. Failed capacitors, especially on hard start kits, can cause the system not to run; you will want to make sure that you have tested all of those accessories. If a compressor has a factory hard start kit, you will want to replace the hard start kit with the compressor; an aftermarket hard start kit may just need to be removed, not replaced. Pitted contactors, switch problems, poor connections, and wire damage can also cause the compressor to run continuously or short-cycle the compressor, both of which lead to early compressor failure.
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