compressor

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JDWALKE
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I have a 95 SL1 Saturn with 78,000 miles. The clutch on the compressor will not engage, unless I bypass the relay. I have check all the fules, relays, etc; This is a new compressor, and I have also replaced the expansion valve, and other parts.

I have read in other forums that the compressor must be charged before the clutch will engage. However, doesn't the clutch have to be engaged to charge the system.
May 3, 2006 at 9:22 PM
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LOSONE
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No the system has to have a complete charge so the pressure switch will turn on the relay and turn on the compressor. That prevents compressor damage. Have it caharged and it should work fine. good luck
May 4, 2006 at 8:20 AM
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PEPPERMRJ
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^^^^^^^^^^^^^What He said!^^^^^^^^^^^^

Be sure to pull vacuum on it for a while before charging. Any moisture left in the system will have bad consequences.

Good luck and let us know. :)
May 4, 2006 at 3:03 PM
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LOSONE
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If the system is totally flat or has a few ounces by all mean evacuate the system. if it needs only one can (12oz) then you can put it in with no problem
May 4, 2006 at 4:54 PM
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JDWALKE
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I charged the system and the ambient temp. is 70, low pressure 65, high pressure 70. It looks like the clutch is trying to engage but i keep blowing a mini-fuse. Not sure where to look for the short, but any ideas would be appreciates.

Thank you for your help so far.

jdwalke
May 4, 2006 at 7:49 PM
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PEPPERMRJ
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If it ran with a bypass on the relay swap out the relay. Next would be to jump the pressure switch connector.
May 4, 2006 at 9:17 PM
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LOSONE
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Opps! The pressures should read low side 35-45 high side 125-175. Verify the pressures with me. It is not a good idea to by pass the pressure switch because soem have a ground/12V problem and you might cause damage.
May 5, 2006 at 5:21 PM
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JDWALKE
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the pressure is withing the limits mentioned by losone. now, when I turn on the AC, I keep blowing a fuse - not sure where the short is. Any ideas to troubleshoot this would be greatly appreciated.

Regard,
jdwalke
May 7, 2006 at 10:16 AM
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LOSONE
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The way it works is this way;
1. Power is applied to the A/C pressure switch on the Lt Grn wire when the A/C sw is turned on.
2. If there is pressure on the switch the power is then sent to the computer on the Lt Blu-Blk wire ECM pin C-10
3. The ECM then provides ground from ECM pin B-4 to energize the A/C relay.
4. Power to the compressor is than applied from the A/C relay on the drk green wire to the compressor clutch.

Please explain exactly when the blown fuse ocurs and under what circumstances. Also explain how you energize the compressor and make it work.

Let me know
May 7, 2006 at 11:12 AM
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JDWALKE
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After starting the car, I turn on the the blower and the a/c. The fuse blows right away.

Also noticed something very strange today when this happens my cooling fan also kicks on, even though the motor is cool.

Additionally, the car also will not idle at times. Not sure if this is related to the problems I'm having with the a/c.

As far as enegizing the compressor, I just turn on the a/c and put two cans of R134a. During this time, the compressor clutch never kicked on.

Thanks Again,
jdwalke
May 7, 2006 at 8:35 PM
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LOSONE
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You have answered the right question. If the coolant fans kick on, as they are supposed to do, the relay and the pressure switch are doinig what they are supposed to do and the computer doesn't have a problem. I am afraid it is the A/C compressor clutch. Good Luck
May 8, 2006 at 6:39 AM