1993 GMC C1500 A/C Compressor cycling

Tiny
MCGWAY
  • MEMBER
  • 1993 GMC C1500
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 99,900 MILES
The air conditioner is cooling as it always has, but A/C compressor is cycling on and off more frequently. Once the inside of the truck cool down, the compressor will cycle on and off every 5 seconds at idle and every couple of seconds at higher RPM. I had heard that the system may be low on R12, but it cools like it always has. I still had a can of R12 and went ahead and added some. It took about 1/2-2/3 of a can. Didn't help, it still cycles rapidly.

I have this truck since new and I know this compressor is suppose to cycle, but it seems to be doing more than it used to. Am I just hearing more things as this truck gets older or is this normal?

Thanks for any help.

Tom
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Wednesday, July 9th, 2008 AT 10:37 AM

5 Replies

Tiny
OBXAUTOMEDIC
  • EXPERT
Check the Cycling Switch.
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Wednesday, July 9th, 2008 AT 11:06 AM
Tiny
MCGWAY
  • MEMBER
Check the Cycling Switch.[/Quote:33137209e6]

Where is this Cycling Switch Located?
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Wednesday, July 9th, 2008 AT 1:57 PM
Tiny
OBXAUTOMEDIC
  • EXPERT
Sorry, was at my county job as an EMT got a call.

It is mounted on the Accumulator it looks like this....


http://www.2carpros.com/forum/automotive_pictures/188069_239154_1.jpg



Here is what the switch look like.....


http://www.2carpros.com/forum/automotive_pictures/188069_239274_1.jpg

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Wednesday, July 9th, 2008 AT 4:34 PM
Tiny
MCGWAY
  • MEMBER
Thanks. I assume that cycling switch is the same as the "Low Pressure Switch." I had that switch, "Low Pressure switch" replaced a few years ago when the compress just shut down. When the mech. Replaced it, the compressor worked fine. So you think this could be the problem? I will go see if the Chev. Dealer has it in stock.
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Friday, July 11th, 2008 AT 4:41 PM
Tiny
OBXAUTOMEDIC
  • EXPERT
To check this jump the terminals in the harness.
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Friday, July 11th, 2008 AT 4:56 PM

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