I tried to test the AC system on my '94 this past weekend. With the temp set at 65 and an OAT of 78 the compressor did not engage. Can someone tell me what I am missing here. Is there programming that won't allow it to operate below a certain OAT temp? Or do I actually have a problem?

 

If the compressor is low on or completely out of refrigerant, it's designed not to engage as a failsafe. You'll need to hook your guages up to it and see how many lbs. of refrigerant you have in your system.

 

This forum is great with some very helpful and knowledgeable members.

http://www.autoacforum.com

Good luck.

 

Here is a long-shot of something to try. The compressor on my 95 started acting erratically last summer but once the a/c was on, it worked fine and stayed on. For no particular reason I decided to remove and re-install the fuse for the a/c and immediately after doing that had NO problems. I don't know that that accomplished but it might be worth a try.

Doug

 

Easy test for low refrigerant:
With engine running and AC ON Max, remove the pressure switch (on the refregerant line) connector and jump it (the connector, not the switch). If the compressor cycles on, then the problem is low Freon.
If it doesn't cycle on, then the problem lies elsewhere....

Larry
code5coupe

__________
I ain't easily impressed....

 

Low gas or no gas should set a trouble code and that's indicated by a flashing LED on the a/c control panel. See Tech Tips for info on retrieving a/c trouble codes. Should there be a code, clear it by disconnecting and reconnecting the battery, then start it up and see if resets. If so post what it is.

If you don't have any codes, it may just be a loose connection at the low pressure switch which seems to be a problem for your Year (and other GM's). That's usually mounted on the Accumulator or the big tin can or on the Evaporator outlet (large line at the top of the passenger side Firewall. Find the harness and disconnect and reconnect it - wiggle it around and see if that gets the compressor to engage. You can ohm out the switch too. If there's enough gas in it, the contacts should be closed with the engine not running; ie, your meter should show a complete circuit. If it does, jumper the harness with a paper clip across the connector terminals. If that gets it running, it needs a better connector. If you have a scanner - the a/c pressure switch should show voltage in excess of .5 volts or in excess of 50 psi.

The other possibility - absent a code - is the compressor relay. If the pressure is above 50 psi and it doesn't run with the low pressure connector jumpered with a paperclip, you might just replace it and see what happens.

 

I don't see any codes. I'll take a look at the fuse and low pressure switch. There's always the possibility I lost the refrigerant during the winter.

Thanks for the info.