My '97 a/c clutch is not engauging, should I see current @ the clutch when ever the a/c is turned on or does the system look for refrigerant pres. etc. before the clutch is energized?
thanks, Louie

 

Power for the A/C clutch is as follows:

Fuse F5 in the underdash fusebox -->> Function selector switch on dash -->> normally closed contacts of the high pressure cutout switch -->> Cycling switch on accumulator -->> to clutch coil. The low side of the coil should be grounded.

Check for VOLTAGE, not current at the clutch.

The cycling switch closes when the internal pressure in the sysem (at the accumulator) rises above 43-45 psi and opens when the pressure falls below 20-25 psi.

The high pressure switch is mounted on the high side hard line and is intended to open and remove compressor power if the high pressure exceeds a safety threshhold, typically 350-400 psi or so.

If pressure in the system is too low due to no or a weak charge, the cycling switch stays open, preventing clutch engagement and compressor damage.

Therefore, yes, the system does "look" at the pressure before allowing the clutch to engage.

You should also. AC system pressure guages that look like a tire pressure guage are inexpensive and are available at auto parts stores everywhere for under $10. They will provide a quick snapshot of the system so you know where to focus your attention.

A properly charged system checked (engine off) with the underhood temps cool will read at least 75 psi and will be up to 100+ psi if the engine is hot.

Steve

 

WOW,
Thank you for your detailed answer. You sound like a true technician I'm sure I will identify my problem with help you provided.

THANK YOU, Louie