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azlincoln79 on Fri June 27, 2008 7:06 PM User is offline

Year: 1995
Make: GMC
Model: k2500
Engine Size: 454
Refrigerant Type: 134
Ambient Temp: 105
Country of Origin: United States

After pulling a vacuum and starting to put freon in I could here a leak coming from the drier. pulled the low pressure switch off and it stopped leaking. After putting a new one on it held a vacuum for ten minutes or so. Put in freon and the compressor ran fine. It did not cool very much. Ran out of time and was not able to get back to it tell yesterday. The compressor is not working. I tried to short out the low pressure switch and could not get the compressor to kick in. There was a bit of oil around switch. Are you supposed to put thread tape on this switch? Is there a o ring that is supposed to go in there? I suspect all the freon has leaked out. This switch is made out of plastic so you can not tighten it much. Just put on new hose,compressor and drier. I know there is a condenser fan on this truck that is broken but that should not stop the compressor from starting. Any suggestions?

mk378 on Fri June 27, 2008 7:13 PM User is offline

There needs to be an o-ring on the fitting that the switch threads onto, in the groove above the threaded part. The switch does not need to be very tight.

azlincoln79 on Fri June 27, 2008 8:14 PM User is offline

Ok I will put one on. Any suggestions on why the compressor would not come on?

Dougflas on Fri June 27, 2008 8:58 PM User is offline

Try disconnecting the battery for a few minutes.

GM Tech on Fri June 27, 2008 9:51 PM User is offline

No codes to set on C'K trucks- battery disconnect won't help- you are jumping the wiring harness that plugs into the pressure switch right?

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

azlincoln79 on Fri June 27, 2008 10:04 PM User is offline

Yes putting a jumper wire across the two little prongs on the wire like you do when first getting the compressor to come on while recharging.

Edited: Fri June 27, 2008 at 10:05 PM by azlincoln79

Chick on Sat June 28, 2008 8:01 AM User is offlineView users profile

After you put the O ring on the cycling switch, you need to pull another deep vacuum, let the vacuum pull in as much as the charge as it can, then start the ac and finish charging, in other words start from the beginning again..Hope this helps..

Email: Chick


Freedoms just another word for nothing left to lose

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