A/C not working

When I turn the AC to Max or just regular setting, and the temp knob is set to cold, i don’t get cold air. I noticed that the AC compressor clutch does not engage. From what I have read on the web, one person replaced the CCRM and this fixed his problem. Appearently, the CCRM ($150.00) controls the signal going to the clutch magnet that causes the compressor to run. But i’m not 100% sure if this is the same problem that I’m having.

I will check the pressure switches to make sure that they are working properly. I don’t want to spend over $350.00 worth of parts (reman. AC compressor, accumulator/receiver-drier, orifice tube/thermal expansion valve, couple cans of R134a refrigerant, and some other misc. parts like o-rings), so first I will check out the electrical side of the system.

If any one has any ideas… please let me know. Thanks in advance.

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Something else that you might want to get is the temp control switch. If you look down by your knees you will see a round object with a cord reaching back underneath the dash (on the center console). Check and make sure that the cable has not snapped loose from the clip.

Do I have to take of the plastic cover to access the center console? Is that where that switch is?

sit in the drivers seat. notice where your right knee is. Look forward about 10 inches and you will see it. it is a 3 inch circle that is stuck to the side of the console.

You do not have to take your console apart to examine it. However, if you have changed you stereo, the connection may have come unplugged from behind. in that case you would need to pull your stereo back out and plug it in again.

OK… I’ll check that out. thanks.

This is what I tried the other night:

this is so weird… it worked last night for like 5 min.
after I disconnected the battery (i thought it might reset the computer) and then hooked it back up:
the compressor kicked-in and cold air started to come out from the vents. Also, the refrigerant lines were cold. At this point I quickly connected the refrigerant re-charging can (R-134a). I noticed that the pressure was in the Blue area (which means you don’t need to add any refrigerant), so I left it alone. (before the compressor kicked-in, the pressure was around 100 PSI) But like I said, after 5 min. or so, the compressor no longer engaged, therefore, the air started to get warm… sucks. I checked the low-side pressure switch and it was fine. But I don’t know how to check the high-side because the pressure switch has 3 pins, so I don’t know which are supposed to be normally opened/closed. Is there an electrical schematic any where?

Check this out:



What was your thought process when diagnosing your AC problem that led you to the Constant Control Relay Module (CCRM)?

I checked the low-side pressure switch and it read OK (it was closed). But the only thing I can think of is the high-side pressure switch that might be bad. But I don’t know how to test that… it has 3 pins and I don’t know which ones are normally closed/opened. So I thought I’ll open up the CCRM and see if there are any loose solder connections. this is just a shot in the dark. Do you guy have any tips on how to diagnose the A/C system?

I will ask my father later. My family is involved in A/C and refrigeration. I dont know enough about it to help you out though. My father maybe able to provide some better input on the high pres switch.

thanks Ironmark

i found this on another forum:

[url=http://www.feoa.net/modules.php?name=Forums&file=viewtopic&t=29744]http://www.feoa.net/modules.php?name=Fo ... ic&t=29744[/url]

i’ll try to diagnose the CCRM tonight, i’ll let you know how i made out.

OK I finally got it fixed…

After reading many, many posts…
this one finally made sense:


Thanks to GM Tech’s post…

Connecting a normally closed (N/C) relay in parallel with the CCRM’s “WOT A/C CUTOFF RELAY (N/C)” will fix this problem if the CCRM’s relay is bad.

This fix saved me $187.00… and I’m really gald that it worked… thanks GM Tech and the other members for your help… it’s greatly appreciated.