A/C inconsistant problem

[azshtr]

Man you guys know everything! Your awsome [img]smile.gif[/img]

Now that I've buttered you all up here is my problem:

A/C works great, most of the time. I have not had the 86 GW long so don't have much experience with it yet. Here is what I do know. The A/C works great most of the time. Sometimes however it won't blow cold... the compressor does not turn on. If I play with the control a bit it then will work. I would suspect the control but about 1 1/2 years ago this problem was looked at by a shop and they indicated electrical problem and replaced the in-dash control unit. My aunt, who I bought the car from, said it didn't help the problem at all. She ignored it due to living in colder climat and it would eventually turn on if she needed it. She fixed everything with prompt attention exept for this problem.

Could it be a coinsidence that it turns on after I play with the control? A relay that finally works after repeated attempts? Or maybe a clutch that doesn't always kick in? Once it works, it works great. Once I turn on the air, it will cycle on and off with no problems. It is just that once in a while it won't turn on the compressor.

Where should I look?

Thanks,

[will e]

Sounds like the control to me. try bypassing the control to see if it solves the problem.

[ulm210]

It might be the a/c clutch. Check the connection of the wire on the clutch at the compressor. if the connection is loose or weak, this can cause an intermittent problem. If this is the problem, check on ebay for a guy who sells oem a/c clutches for $25. It is under "parts and accessories" and type "Wagoneer".

[Wesdog]

Does the AC blower work when this happens? If so then power is getting to the Ac Control unit. The best way to troubleshoot this is to make some voltage measurements when the problem is present. Disconnect the compressor clutch and measure the voltage between the harness side of the connector and ground/chassis/battery negative. If 12 volts is present then it's probably the clutch unless there is an intermittant harness connection. If you get zero volts then you need to start tracing it back. There is a fuse between the compressor clutch and the controls, check that also. Look here for wiring diagrams:

http://209.238.200.129/gw/elec/GW_wiring.html

Wesdog

[azshtr]

Thanks for the help. Wesdog, yes the blower works, it just blows warm air. Its definatly the compressor that is not turning on. Checking for voltage at the compressor when this happens seems logical, why didn't I think of that? Now I just need to have a voltage meter with me at all times. Of course if I'm ready for it and want it to happen again it probably won't.

If it is the clutch, how hard is it to replace?

Thanks again [img]smile.gif[/img]

[Wesdog]

I haven't changed an AC clutch so I don't know.

If you figure out which fuse is the compressor fuse beforehand, then when the problem occurs measure the voltage both the input and output of the fuse with reference to chassis and that will tell you if the controller is suspect. If you measure 12 volts at the compressor fuse when the problem is present then that eliminates a few possibilities and you don't have to disturb anything to make that measurement. You might want to measure it now and even pull it to confirm it is the correct one.

Wesdog



[ August 08, 2003, 05:16 PM: Message edited by: Wesdog ]

[TexasJ10]

A simple test light would also tell you whether power is making it to the clutch.

[Wesdog]

Yes, you can use a test light. I don't use test lights because my training is as an electronic technician and I always want to know the actual voltage reading. Test lights are like idiot lights and they don't provide real test info, using them as an absolute indication can be deceiving.

Wesdog

[Stolen76]

Run a hot wire to the clutch and see if it locks in consistently. You can also pull the plug on the temperature control and jump it across. It would be my guess as to the failure. Not the in dash control, the one that's by the expansion valve. They are notorious for the symptoms you have.

[will e]

I doubt that your clutch works intermintently. When you're having problems, I bet you will not have any voltage to the clutch.

[Michael]

I would check the high pressure switch...the switch by the sight glass. Make sure it is making good connection. There is also an ac relay in the far left vent. You may need to test that.

[azshtr]

I knew you guys would be full of info. Thanks for the help.

[Wesdog]

I didn't see a high pressure switch in the 86 AC electrical diagram: http://209.238.200.129/gw/elec/86/86...ramPage3-3.gif

Doesn't mean there isn't one. I had one added to my 76'

Wesdog

[azshtr]

Thanks for all the help. Now its not doing it? But I will know where to look when it does. Thanks again.

Dave

[Michael]

Originally posted by Wesdog:
I didn't see a high pressure switch in the 86 AC electrical diagram: http://209.238.200.129/gw/elec/86/86...ramPage3-3.gif

Doesn't mean there isn't one. I had one added to my 76'

Wesdog

Hmmm my 87 has one....