A/C clutch won't engage - TCCoA Forums
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post #1 of 3 (permalink) Old 06-01-2016, 11:50 AM Thread Starter
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A/C clutch won't engage

I have a simple A/C question. My clutch won't engage, and I suspect that I am low on freon. I want to manually override the clutch. A quick google search shows how to do this by bypassing the clutch relay, but I do not find such a relay in the box under the hood. I have the automatic climate control. Is my best option just to hotwire the compressor straight to my battery? If so, which terminal is positive vs. negative on my compressor connector? i hope to be able to engage the clutch and then add freon to see how quickly it leaks down before I take it to an A/C shop that will probably charge $200-300 just to check it out and recharge it.


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post #2 of 3 (permalink) Old 06-01-2016, 02:59 PM
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I'll tell you on one condition: please, please, please, please don't permanently hotwire the cycling switch closed.

That's how my original compressor died - it was low on refrigerant and a previous owner permanently wired it closed, causing the compressor to run 100% duty cycle while low on refrigerant. I didn't realize until it was too late, and it was a lot of $$$$ to rebuild the entire system.

The cycling switch is on the accumulator - near the firewall on the passenger side. Get a buddy to watch the clutch for you after you disconnect the electrical connector and jump it; if you hit a/c in on the climate control head the clutch should engage. As soon as you can positively verify that it does work (this will allow you to confirm that the electronics of the system are still good) kill the a/c so you don't damage the compressor in case it is low (or out!!) of refrigerant.

For the cost of someone else to charge the system (assuming this is indeed the problem), which is usually $150-$200, you can get all the equipment you need to evacuate and recharge the system yourself. A vacuum pump/manifold gauge set can usually be had in a combo for about $150; three 12 oz. cans of R-134a are enough to refill from empty and are usually about $10 each.

Note though that if you DO find that it's low on refrigerant, there's a leak somewhere... And finding and fixing that will also cost $$$. Usually you have to fill the system first with a UV reactive dye additive so you can search the system after it leaks down again to pinpoint the leak. IMHE it's often an O-ring; a o-ring set is usually only a few bucks and you can replace them yourself. Use Nylog Blue (if you can get it) to lubricate the new rings instead of PAG 46 oil. If you crack open the system you should also replace the accumulator as it has a desiccant in it which will quickly saturate if left exposed to the humidity in the atmosphere.

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post #3 of 3 (permalink) Old 06-02-2016, 11:46 AM Thread Starter
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This would definitely not be a permanent solution. I am just wanting to force it on so that I can add freon and see if that is my problem. Thanks for all the other input.
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