Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Compressor HVAC: Testing and Inspection

Unlike engine oil, no cleaning agent is added to the compressor oil. Even if the compressor is run for a long period of time the oil never breaks down as long as there is nothing wrong with the compressor or the A/C system.

Inspect the extracted oil for any of the following conditions:

1. Color change from clear to dark brown or black.
2. Presence of foreign substances, metal filings, etc. in the oil.

When the oil extracted from the compressor is found as mentioned above the receiver drier must be replaced.

NOTICE: Failure to replace receiver drier will result in damage to new compressor.