Chevrolet Suburban AC Issue? Weird!

Hello there everybody! Let me start by saying that I'm happy to be joining your online community.

I have a 1997 Chevrolet Suburban 1500 4X2 (C1500). The entire air conditioning system was replaced about six months ago. When I turn on the AC, it blows but isn't cold. The blower is working fine (for both the front and rear), but it won't blow cold. I replaced the AC relay in the underhood fuse panel. I checked and rechecked the R134A to ensure that there's enough in there. I checked all AC and blower-related fuses and things seem to be in order.

Here's what makes this situation odd. The previous owner, my mother, took the truck back to the person who replaced the entire AC system after it stopped blowing cold. The guy hooked a wire up, right in front of her, between two points somewhere in the car (she thinks he did it under the hood, but isn't sure) and suddenly the AC blew cold. So there doesn't seem to be a problem with the compressor. It looks like it's some sort of switch or something that communicates between the AC controls and the compressor to tell it to kick in. The guy who looked at the truck and proved to my mother that the AC blows cold.

So here's the ultimate test (almost a riddle) for anybody who knows a lot about car AC systems. If the blower is working just fine, the R134A is full, the fuses and relay are good, the AC system is 6 months old, and the system blows cold when a jumper wire is hooked up between two parts of the car, what could the problem be?

This should be interesting Thanks for the help!

Sincerely,
Zach

Well does the compressor even kick on? Leads me to beleive he jumped the clutch cycling switch.

When I turn the AC knob on, the pulley on the compressor is turning (of course), but the end part of it that I guess connects to the clutch doesn't engage. There's no clicking noise and the small plate on the end of the pulley doesn't begin turning. Could that be the problem then? And is there any way to fix it that isn't buying a whole new compressor?

Thanks so much for the help! I live in Florida and it's hot as hell!

Zach, There is a wire that goes to the back of your compressor clutch. Check to see if it is still attached. If it is, pull apart the clip and use a test to see if power is getting to that point. My guess is that there is not power. If not, you should check the switch ( the button that activates the AC) to make sure the power is going through it. (Those switches can go bad)

I hope one of these will fix it. Good Luck!, Dondobe

Dondobe,

Thanks for the reply! I'm going to take a look at it this afternoon, and will post the successful/unsuccessful results here this weekend!

Thanks!!
Zach

Hello everybody!

Apparently the clutch on the compressor just wasn't getting power. The wire that gives it power (that runs through the dash switch) wasn't live, so I tested the clutch by running it directly to the battery. Low and behold, it works!

Now I just need to take the time to find where the wire is disconnected. Thank you so much for your help!! :)

Sincerely,
Zach

quote:

ORIGINAL: Zach

Hello everybody!

Apparently the clutch on the compressor just wasn't getting power. The wire that gives it power (that runs through the dash switch) wasn't live, so I tested the clutch by running it directly to the battery. Low and behold, it works!

Now I just need to take the time to find where the wire is disconnected. Thank you so much for your help!! :)

Sincerely,
Zach

Well it's not going to get power if say one of the switches is bad. I would definatly trace down that wire though and see if you can see if it's somehow disconnected, broken, or shorted somewhere. Have fun.

I had a '94 Suburban that had a similar issue. I found that the small pigtail plug that comes out of the top (front) of the compressor had a break (open) in the wiring inside of it. I unplugged it and hard wired (soldered) the wires to the pins sticking out of the compressor, then put a nice blob of silicone sealer over it. Now, a guy who wasn't a shade-tree mechanic like me would buy a used hunk of harness at a wrecking yard (or at the dealer for a probable ridiculous price) and splice it into the original wiring.

This is probably the wire you found at the dash-end with no power. It sounds like you may have found the problem. Way to go.

Thanks for all the replies! They've been very helpful!

I had another quick question. I wired a switch up to my dash to connect the battery directly to the clutch. This seems to be working just fine. However, I keep forgetting to turn the switch off when I get out of the car! And I'm under the impression that if I leave the AC clutch activated 24/7, it may end up damaging it.

Does anybody know if this is true? Will leaving the switch on accidentally damage the AC clutch?

Thanks again!
Zach

If you really want to leave the wiring in a "quick-fix" configuration, why not hook the clutch to a wire that is only "hot" with the ignition in the "on" position? Then when you turn off the key, there is no power to the A/C clutch...

I'll try that. Thanks!

I decided not to go with a quick-fix since it would be best to wire it in as it originally was.

I was reading about.com in my extensive research into this problem, and found a topic that said the following:

---

http://experts.about.com/q/GMC-Repair-813/97-GMC-Suburban-AC.htm

Expert: Jim Gautreau
Date: 6/14/2006
Subject: 97 GMC Suburban AC

Question
The AC compressor on my 1997 GMC Suburban will not engage. It appears that there is no power to the compressor clutch. I have checked all of the fuses I can find and I have replaced the AC relay under the hood. It will not engage when I press the AC button or when I turn on the defroster. All of the fans inside work.

Answer
You either have a low charge which is preventing it from working, or the low pressure cycling switch is stuck. The switch is on the accumulator near the passenger side firewall. Try useing a paper clip to jump it and see if your A/C works. If it does then you need to replace that switch.

---

After reading this response to another person's identical problem, I decided to investigate the possibility that the low pressure cycling switch is stuck. I hooked my multimeter up to the cable that provides power to the AC clutch and there is no power running to it. Therefore, I think that the problem may lie with the low pressure cycling switch. Does anybody know anything about this? More specifically, what the switch looks like and how I can check it?

Thanks again everybody!!
Zach

It's what I said you should check in like my first post in this thread. All you need to do is jump the wires and see if the compressor engages.

Do you mean jump some wires between the battery and the clutch? Sorry, I'm not very savvy on AC systems (or electrical systems for that matter). Which wires should I jump, and where?

Thanks again buddy!

Pull the connector off and jump those wires with the a/c on. If the compressor clutch engages then that switch is bad.

Which connector do you mean? Is it the one that goes into the accumulator? I'm sorry, I've been looking for quite some time at my engine and I can't determine which switch or connector you're referring to. Thank you very much! :)

yes that's the one.