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Old 04-04-2010, 06:34 PM   #1
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Default A/C compressor not engaging

96 Bonnie SE 3800

The A/C compressor is not engaging. I checked the freon level and it is 30 psi. How can I trouble shoot this. I checked all the fuses 1st and they are good. The compressor does not make any noise. How can I trouble shoot this. Is there a way to jump the compressor to make it engage.

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Old 04-04-2010, 06:52 PM   #2
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your freon is low.
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Old 04-04-2010, 08:48 PM   #3
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One of the symptoms of a non-working A/C system is lack of voltage to the A/C compressor clutch circuit. This test requires use of a multi-meter to determine if you have 12volts DC at the connector for the A/C clutch.

It helps to have your front end up on ramps, or at least sitting on jack stands. This gives you plenty of room to get underneath to disconnect the connector for this test.

For safety reasons, it is best to do these steps in order. Failure to do so could lead to having your hand come in contact with the moving accessory drive belt.

Step 1- Disconnect the electrical connector from the A/C clutch.



Step 2- Turn on your multi-meter, set it for 20V DC and connect to the electrical wire that you just disconnected. NOT the connector on the compressor.

Step 3- Start car and turn your A/C on to MAX.

Step 4- Verify 12-13 volts on your meter.
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Old 04-04-2010, 11:00 PM   #4
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Quote:
Originally Posted by Mike1995 View Post
One of the symptoms of a non-working A/C system is lack of voltage to the A/C compressor clutch circuit. This test requires use of a multi-meter to determine if you have 12volts DC at the connector for the A/C clutch.

It helps to have your front end up on ramps, or at least sitting on jack stands. This gives you plenty of room to get underneath to disconnect the connector for this test.

For safety reasons, it is best to do these steps in order. Failure to do so could lead to having your hand come in contact with the moving accessory drive belt.

Step 1- Disconnect the electrical connector from the A/C clutch.



Step 2- Turn on your multi-meter, set it for 20V DC and connect to the electrical wire that you just disconnected. NOT the connector on the compressor.

Step 3- Start car and turn your A/C on to MAX.

Step 4- Verify 12-13 volts on your meter.



Mike...I just checked the voltage and it was really fluxuating.....08-1.98.
This is way low so what does this mean?
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Old 04-05-2010, 07:46 AM   #5
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It may mean that something is wrong somewhere else. Lets conduct another test.

The pressure switches are located in these locations.
Lowside switch, up on the accumulator, near the passenger side strut tower.

CAUTION THIS TEST IS TO BE DONE IN A SHORT AMOUNT OF TIME. NOT TO BE LEFT RUNNING WHILE DOING THIS TEST.
Disconnect the connector and use a paperclip or homemade jumper wire to jump the connector. Not the switch itself. Once this is done, proceed back to the same test as you had done earlier. If you do see 12V at the A/C clutch connector, go ahead and connect it to the compressor. If it starts running, immediately disconnect it. This will mean 1 of 2 things, either have have low pressure in the system, or your switch is bad. Let us know what happens and we will proceed from there.
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Old 04-05-2010, 03:00 PM   #6
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This model does not have the low pressure switch at the accumulator. I did find one behind the compressor on one of the lines going into the compressor. I'm guessing this is it and it is a three wire and jumping different combos I got the cooling fans to come on. The other two combos resulted in the volts being 3.5.
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Old 04-06-2010, 01:55 AM   #7
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Problem fixed sort of.

I found another thread that Bob Keys had the same problem. No pressure switch at the acummulator but a three wire switch at the compressor. I followed his lead by jumping the red to tan wire that goes to the switch which makes the fans come on. Then I jumped the compressor to the battery and the clutch engaged. I put a 12oz can in (with a/c on max) and the pressure came up to 27. With the A/C
off the pressure was 65. I let run for about ten mins and added some of a second can but the pressures stayed the same 27 with a/c on and 65-70 with it off. The air coming out of the vents is really cold. I took the jumpers off and reconnected the plugs and the clutch engaged fine. All seems to be ok but the fact that the pressure will only go to 27 makes me wounder if there is a big leak somewhere. I'll recheck it tomorrow. What do you think about the pressure not going any higher than 27?

Thanks for all your help guys
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Old 04-06-2010, 06:58 AM   #8
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Oh thats why I couldn't get why you didn't have another switch. Duh, I thought you had a 95. My bad.

Not sure on the pressure requirements for yours though. Someone else may know something more.
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Old 04-07-2010, 12:00 AM   #9
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Does anybody have the figures on what the low side pressure should be for my 96 Bonne SE.

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Old 04-07-2010, 08:07 PM   #10
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My fsm says 37F at 70 degree ambient temp and 20 % humidity. I prefer 30 to 35 myself.
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