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Chrysler Repair/'99 Concorde: A/C won't activate


QUESTION: My air conditioning suddenly stopped working. I have read several forums, so I have ruled some things out.
- The heat and the vent still work fine, so it is not the blower motor.
- We tried recharging it and it took some 134 but not much.
- I have checked all the fuses, they are fine. Also my brother checked and it is getting power.

- It seems that the a/c clutch never comes on.  A forum suggested that there is a single analog sensor that sends voltage to the PCM. You should "trick" the clutch into coming on by applying 12 volts to the right pin of the 4 pin connector going to the clutch (The blue wire with the black stripe).  First of all, is this correct? My brother tried doing this but it is possible that we were trying the wrong pin.  If it is correct, then I have two questions. 1. if it works, does it mean that it is the analog sensor that is bad? 2. If it doesn't work, then does that mean the clutch needs replaced?

ANSWER: Hi Katie,
On the compressor clutch: first check fuse B (30 amp) in the power box in the engine compartment. Then remove the compressor relay in the same box (relay #10, located behind fuse F and G) and then jump a wire from pin socket B to  pin socket D in the relay socket (B and D are side by side). That should activate the compressor clutch. The clutch should click even when the engine is running when you do this test of it.
I would test the clutch that way, as I don't see the 4-pin connector or the blue/black wire that you described. If the fuse is good, and the wire from pin D to the clutch is good and the black wire at the clutch plug is connected to ground, then the clutch is bad. Otherwise there is an issue with the refrigerant pressure level in all likelihood. How do you know that you put in enough R 134? I would not simply replace the pressure sensor, but rather measure the actual pressure in the system.
Please 'rate/nominate' this answer/me (see the PS below).

---------- FOLLOW-UP ----------


Thank you.  I have already checked the fuse B (30 amp) in the power box in the engine compartment. My brother also verified that it is getting power up to that point.  He also checked the compressor relay in that box. He did not jump it, but he did replace it with another working one to verify that it should work, and checked that it was getting power to that point.  

I thought there was enough R 134 because we filled it until it wouldn't take anymore. However this could be wrong since the clutch wouldn't kick on to accept more.  That is why I was thinking the pressure sensor is out because it thinks there is too low of pressure so it won't kick on (which is why some forums suggested jumping that to force the clutch on).  I will play with it some more and get back to you.  

Thank you for your timely response.

Hi Katie,
Do try the jump across B and D in the socket for the a/c compressor relay as a final test of the clutch. It is possible also that the system is too full (pressure too high) as that sensor will only give a go ahead in a specific pressure range.
You are welcome. Thanks for the rating and nomination.

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Roland Finston


Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

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