AC Compressor won't engage, any help?
08-02-2008, 06:50 PM
#1
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AC Compressor won't engage, any help?
Hello all,
I'm having some problems with my AC which I believe to be related to electrical issues and I'm hoping that some of the wisdom on the board can help me track them down. The car is a 1986 944 Turbo, and here is what's given:
1- The air mixing door is closed as it should be, I replaced the clip on that rod last year and it has all been working fine, I inspected it recently and it's still holding up fine.
2- It has a full charge. I put about a can and a half in to top it off about 3 weeks ago.
The issue that I'm having is that the compressor won't stay engaged. When I press the button inside the car to engage the AC, sometimes it comes on, and sometimes it doesn't. I started noticing it about a week ago when I noticed the engine surging at idle. It would fluctuate from about 800 rpm to 1000 rpm, through some experimentation I realized that it only happened with the AC engaged. My assumption is that the surge came from the clutch engaging (the drop) and disengaging (the rise).
The problem has gone a step further now and the AC switch on the dash will only bring the compressor online for about 3 seconds and then it drops back off and stays off- when the compressor does come on, I feel cool air coming out of the vents immediately, so the cooling system is definitely working when it's all running.
What can I do to troubleshoot the electrical circuits in the system to find out where my fault is. Does anyone have a diagram or a link that I can follow? How can I test my AC Relay?
I've looked on Clarks-Garage and can't find anything useful about the AC system for this particular situation. Thanks for the help.
I'm having some problems with my AC which I believe to be related to electrical issues and I'm hoping that some of the wisdom on the board can help me track them down. The car is a 1986 944 Turbo, and here is what's given:
1- The air mixing door is closed as it should be, I replaced the clip on that rod last year and it has all been working fine, I inspected it recently and it's still holding up fine.
2- It has a full charge. I put about a can and a half in to top it off about 3 weeks ago.
The issue that I'm having is that the compressor won't stay engaged. When I press the button inside the car to engage the AC, sometimes it comes on, and sometimes it doesn't. I started noticing it about a week ago when I noticed the engine surging at idle. It would fluctuate from about 800 rpm to 1000 rpm, through some experimentation I realized that it only happened with the AC engaged. My assumption is that the surge came from the clutch engaging (the drop) and disengaging (the rise).
The problem has gone a step further now and the AC switch on the dash will only bring the compressor online for about 3 seconds and then it drops back off and stays off- when the compressor does come on, I feel cool air coming out of the vents immediately, so the cooling system is definitely working when it's all running.
What can I do to troubleshoot the electrical circuits in the system to find out where my fault is. Does anyone have a diagram or a link that I can follow? How can I test my AC Relay?
I've looked on Clarks-Garage and can't find anything useful about the AC system for this particular situation. Thanks for the help.
08-04-2008, 03:26 PM
#2
You could try jumping the relay and see if the compressor stays on. Could just be a bad relay. There are also pressure switches in the A/C system that don't let the compressor turn on unless the system is charged, so the compressor won't burn up. Do you have any way to verify if the system is holding pressure, like a A/C pressure gauge, if bypassing the realy doesn't work?
