Appendix; Compressor Failure; Compressor Replacement - Desert Aire SelectAire Plus SP Series Installation And Operation Manual

5.

Appendix

5.1 Compressor Failure
Although most compressors fail because they are mechanically flawed, most failures are due to
system-related problems. Compressor failure can be caused by liquid flood back, air or moisture in
the refrigeration system, solid contaminants, excessive heat or electrical service malfunctions. To
avoid repeated callbacks, you must determine the cause of the failure and then correct it.
If the compressor has failed because its motor has burned out, the refrigerant, oil, and piping may
have become severely contaminated. If a burnout has occurred, use the following procedure to
replace the compressor and clean the refrigerant system. Use an oil test kit to determine the severity
of the burnout. Make sure you use rubber gloves and eye protection, as contaminated refrigerant and
oil can cause severe burns!
You must clean the system thoroughly to prevent repeated compressor burnouts.
5.1.1 Compressor Replacement
Desert Aire dehumidifiers are designed with scroll compressors. Scroll compressors are
known for operating more reliably than other compressors in air conditioning and
dehumidification applications due to their ability to cope with occasional periods of liquid
refrigerant return. There are fewer moving parts in a scroll compressor subject to wear
compared to alternative compressor designs. Nonetheless, there are still many mechanical
and electrical parts with close tolerances. Replacement of the compressor may be required
during the normal service life of the dehumidifier.
Inspection and Initial Diagnosis
Generally, the compressor will have two basic failure modes, mechanical or electrical. The
compressors are a hermetic design, meaning all components, including the motor, are in a
sealed shell. It can be very difficult to determine which issue was the root cause of the failure
in the field by inspection of the damaged compressor. For example, an initial bearing failure
inside the compressor may create debris that contaminates motor windings. High current
draw may be related to a bearing issue or a motor winding issue. The initial inspection must
be combined with a final analysis of the machine when returned to working order to conform
diagnosis.
Specific items should be noted before the replacement to give the best indications of the
failure and complete the diagnosis as the new compressor is installed. The following data
should be taken to assist in diagnosis:
• Current draw for each leg of power (if the compressor will run and pump).
• High side and low side pressure (if the compressor will run and pump).
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Desert Aire - SP Manual