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Trouble with pressure switch

Scout3 on Sun September 18, 2011 10:56 AM User is offline

Year: 1994
Make: Chevy
Model: K1500
Engine Size: 5.7
Refrigerant Type: 134

My A/C has been working fine, but the last year I have had touble with the pressure switch. Pressures were good but sometimes it would fail to turn on and I would have to tap the pressure switch and it would kick on. It would kick on and be okay for a few days. Finally decided to replace the switch. It is on the accumalator by the firewall. I removed the switch as it had a air fitting underneath. Now when I try to put the new switch on it blows freon before I can get it threaded on. Do I have to have the system drained just to change this switch?


mk378 on Sun September 18, 2011 12:27 PM User is offline

Is the o-ring properly in place on the fitting? Use a new o-ring and put oil on it.

Scout3 on Sun September 18, 2011 4:03 PM User is offline

Has a new oring and it is now covered with mineral oil. I will stop at a small ac shop on the way home tomorrow. I tried to push and turn and it caught the first thread and then blew it off. I guess I lost about 1 oz of freon. Turning a simple job into a big one.

GM Tech on Sun September 18, 2011 6:32 PM User is offline

It is normally the connector on the switch not making good connection.....I see it a lot on those-- try to bend tabs into a tighter fit..

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......

Scout3 on Sun September 18, 2011 8:02 PM User is offline

I already verified the wires and cleaned and bent the pins a little and it still did it. I was just wondering if there was a trick to getting the switch on. I even jumpered the plug and tried it with the A/C running hoping the pressure would be lower. Still could not get it.

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