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XtraGassy

Air Conditioning Compressor Clutch Not Engaging

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Hello. I just joined and this is my first post. I have searched the forum and cannot find the solution to my problem. I recently bought a 2000 Contour Bi-fuel. The car is great, but there is one problem: the AC clutch will not engage. Before I took it home, the dealer tried to fill the system with R134a only to find that it was full. I have performed the following tests and have yet to find the problem.

 

1) Tested the relay (R3) and it works just fine.

2) With the relay removed and engine running, set the car to Max AC. Jumped the control circuit (pins 1 and 2) and the measured current is 20mA. The blower motor comes on and the air recirculation solenoid valve engages (audible).

3) Jumped the air conditioning circuit at the relay with the engine running, but the clutch does not engage. Voltage through the relay (pins 3 and 5) is 13.4V and voltage across the battery is 13.8V.

 

Its not the relay and it isn't the HVAC controls. I'm getting good voltage across the circuit and the clutch still does not engage. I believe this also eliminates upstream circuitry as the culprit. Looking at the wiring diagram the only thing between the relay and ground are the:

 

1) compressor solenoid

2) compressor diode

3) the compressor itself

 

One of these 3 must be the problem, but I'm not sure how to test them. Some questions:

 

1) Is it possible that the 13.4V across the circuit is grounded through the diode only and no power is going through the solenoid?

2) What is the function of the diode and will a bad one keep my compressor clutch from engaging?

3) What should the clutch gap be?

 

Any help would be appreciated. Thanks.

Edited by XtraGassy

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Update:

 

I took a screwdriver to the compressor with the AC on max and there was sufficient magnetic force to attract my screwdriver and suspend it. If the solenoid is getting enough juice, why isn't the clutch engaging?

 

HELP!

 

PS - I probably just need a new compressor. Anyone have a reference source to find out which cars have compatible units?

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Update 2:

 

With the AC on max, I gave the compressor clutch a little nudge and it was able to engage. This was about 10 minutes ago and I think the air is starting to cool. Is this a clutch gap issue?

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Update 3:

 

Though the clutch engages, the system continues to blow hot air. Clutch engagement does not seem to increase the load on the engine. Similarly, disengaging it does not seem to decrease the load. I am going to replace it with a compressor unit from the junk yard.

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I think you have your answer!!! In using a replacement compressor, atempt to locate a vehicle that has yet to have the AC lines broken - lessens the chances of moisture contamination within the normally sealed AC system, and possibly a bad used compressor. I realize this might be a tall order, but it is possible.Careful when removing the electrcial connector on your 'Tour where it connects to the compressor. Easily damaged connector.

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Thanks for the advice, mondeoman. What do you exactly mean by "easily damaged"? I already broke the turn signal connector for a headlight. The condition of the plastics in the engine bay confirm that this car is indeed 15 (almost 16) years old.

 

I am planning to use a 12v battery pack (a radio shack doodad holding 8 AA batteries) to jump the compressor to test for clutch engagement. Would anyone advise against that?

 

And considering that I have to discharge the system, it would probably be worth my time to pick up an eBay seal kit for $15 and overhaul the entire system. Is it absolutely necessary to replace the evaporator, too? Can I just let it dry out or clean it somehow?

 

Also, I understand the compressor units from the following cars will fit my car. If you know of any others, please chime in:

 

1) Any 2.0L Ford Contour (duh) or Mercury Mystique 1995-2000

2) Any 2.0L Mercury Cougar 1998-2002

3) Any 2.0L Ford Escape or Mazda Tribute 2001-2004

 

PS - I hope this conversation I had with myself helps someone else diagnose their AC problems. I like to think I went about it the right way.

Edited by XtraGassy

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I was referring to the electrical connecotr on the compressor - easily broken for the reason you site as well as not obvious how to release it.

 

Well if you locate a sealed system, this is the way to go. If you have the time, it would be advisable, but not absolutely necessary, to install new o-rings. I have been fortunate twice now to install just the compressor and then recharge - perfect operation.

 

I think you pretty much hit the interchangeability square on!! You could perform a cross-reference search on Google using the compressor model number.

This MIGHT reveal more interchange than you list.

 

Oh this conversation is very helpful - keep the info flowing!!

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