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HVAC School - For Techs, By Techs

Apr 17, 2018

In today's podcast, we talk with Trevor Matthews with Emerson. He tells us about the causes and prevention of air conditioning and refrigeration compressor failure.

Most compressors don't die a natural death... they're murdered. Of course, that's to say that installation and maintenance play a major role in the compressor's operation and lifespan. Electrical and mechanical failures are the two broad causes of compressor failure.

When it comes to electrical failures, Trevor often sees single-phase compressors fail early when their electrical components don't receive proper inspections and care. For example, contactors may go too long without inspection or replacement. Three-phase compressors are also prone to phasing issues and may run backward.

Common mechanical failures deal with oil in the system. Oil lubricates the bearings inside the compressor. Unfortunately, that oil can mix with liquid refrigerant, become diluted, or experience acid contamination. Some oil-related failures include floodback, flooded starts, slugging, overheating, oil loss, and contamination. Compressors cannot compress liquids, so many of them fail when the refrigerant condenses to a liquid inside the compressor.

Many failures occur because technicians don't think they have enough time to troubleshoot or inspect the whole system. Trevor recommends setting up a checklist with all of the tests you need to perform.

Trevor also discusses:

  • Service replacement compressors vs. OEM compressors
  • Megohmmeter usage
  • Causes of floodback/flooded starts
  • Compressor superheat
  • Suction accumulators
  • Bearing wear
  • Temperature control and pump cycles for controlling flooded starts

Verifying System Operation Sheet from Emerson