A/C clutch not working - Ford Mustang Forum
 
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post #1 of 13 (permalink) Old 4 Weeks Ago Thread Starter
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A/C clutch not working

I have a 98 mustang and the clutch will not work. I have tried the low pressure switch and I have tried the high pressure switch and the a/c clutch will still not come on.

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post #2 of 13 (permalink) Old 4 Weeks Ago
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Is there key on, AC on +12 volts at the low pressure switch? Where to go next depends on this test result.


2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #3 of 13 (permalink) Old 4 Weeks Ago Thread Starter
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The car is running and a/c on when I tried jumping the low pressure switch but I did not check it for 12 volts. I will try that tomorrow and post if I find something.

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post #4 of 13 (permalink) Old 4 Weeks Ago
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I'm guessing you've checked all the fuses at this point. I'd try back probing the wires at the A/C clutch with a test light (with key on, A/C on, engine off) to see if you're getting power to the clutch assy. Without a wiring diagram, I'm not sure which wire supplies power and which is the ground. If you have power there but still no clutch closing, disconnect the plug, jumper from the battery positive to the + wire on the clutch. If it isn't shorted out, it should close each time to touch power to the connector.
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post #5 of 13 (permalink) Old 4 Weeks Ago Thread Starter
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Ok I will try that and see what I get

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post #6 of 13 (permalink) Old 4 Weeks Ago Thread Starter
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I have 12 volts at the low pressure switch but do not have 12 volts at the a/c clutch. I have not used a jumper wire from the clutch to the battery yet

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post #7 of 13 (permalink) Old 4 Weeks Ago Thread Starter
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I just tried jumping the a/c clutch and it did not move

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post #8 of 13 (permalink) Old 4 Weeks Ago
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Quote:
Originally Posted by 93redmustang View Post
I just tried jumping the a/c clutch and it did not move
Should I assume that you injected +12 volts to the AC clutch BK/Y wire and the clutch did not engage? As well as when tested there isn't any power at the AC clutch BK/Y wire?

IF the above is true this would likely point to a grounding problem at G101 and G104. IMO to avoid replacing parts that are not broken, TEST the clutch BK wire (ground) to confirm it's ability to carry a current. Use a test light that will "load" the circuit.

Another way to test this is to jump and also provide a ground to see if the clutch engages.

OBTW, the fact there is +12 volts at the low pressure switch confirms that the AC system has basic power.

IF the AC clutch has been confirmed good AND the clutch ground has been confirmed good, I would likely replace the CCRM.

Here's some information on how to use an alternative voltage drop method to test ground circuits.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-for...-drop-test.56/

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #9 of 13 (permalink) Old 4 Weeks Ago Thread Starter
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Come to find out that I was jumping the wrong wire this hole time. When I jumped the black wire with the yellow strip the a/c clutch moved so where do I go from here

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post #10 of 13 (permalink) Old 4 Weeks Ago
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Please re-read my reply.

IF the AC clutch has been confirmed good AND the clutch ground has been confirmed good, I would likely replace the CCRM.

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #11 of 13 (permalink) Old 4 Weeks Ago Thread Starter
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Ok I was hoping it was not the CCRM but I also had an idea that it was it.

Can I rig the a/c clutch with a relay to turn the clutch on and off until I get a new CCRM for the car

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post #12 of 13 (permalink) Old 4 Weeks Ago
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I wouldn't. It seems like a ton of work to "hack up" good wiring for questionable short term gain. This also increases the possible number of trouble shooting variables. This goes double if you plan on replacing the CCRM anyway.

If you are into re-wiring, then consider performing a board level repair of your existing CCRM. The relay can be de-soldered and replaced (don't ask me about which parts to use or more instructions).

If looking for a salvage yard replacement try searching car-part.com.

Four Seasons Relay 37514 $159.00
https://www.autozone.com/cooling-hea...10736_414018_0

FOUR SEASONS 37514 $119.00
https://www.rockauto.com/en/moreinfo...251892&jsn=258

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.

Last edited by wmburns; 4 Weeks Ago at 10:10 AM.
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post #13 of 13 (permalink) Old 4 Weeks Ago Thread Starter
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Ok but thank you for your help

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