95 SIERRA A/C PROBLEM

[beebow]

Just wondering if anyone else has run into this problem: My A/C gave out on my truck recently. The fan and heater work fine, but the compressor doesn't kick in when you press the A/C button. That part sounds simple, but just before this occured the A/C would cycle on and off intermittently. This happened for a few months, then one day nothing. My first thought is the selector unit in the dash. Is there a way to test this? Is there a way to test the compressor? Thanks for any input. 95' 5.7 Sierra Z71.

[Wingnut]

Does the compressor kick on when you turn on the defrogger?

[beebow]

Nope

[carguru]

Just from the description of the compressor cycling before quitting, it sounds like your refrigerant level was low. When the refrigerant drops to a certain level, the compressor would cycle on and off. If it drops beyond that level, the compressor would not come on in order to protect itself. You probably have a leak somewhere in the system. Given the age of the truck, that is a distinct possiblity. I would recommend taking it to someone who can service the A/C. Otherwise, you might want to get a guage to measure the refrigerant level in the system. If it is a low refrigerant level, you will have to trace the source of the leak and fix it before recharging. If the leak is not fixed, you will have to recharge the system again soon. With this method, you risk damaging the compressor due to any moisture that may have gotten in the system.

[carguru]

Oh, BTW, was the A/C blowing out not so cold air before it started cycling on and off?

[beebow]

Thanks for the responses. The A/C was cold, but I may have gotten used to it getting a little less efficient over the years. Any suggestions on a good shop in the Phoenix area? I try to do most repairs myself, but don't have any experience with A/C.

[beebow]

I jumped the switch on the accumulator and the compressor clutch kicks in, but the air is not coming out cold. Does this mean that the compressor may be ok, and the charge is just low?

[OUMike]

Beebow,

The problem you describe is IDENTICAL to the problem I'm having with my 94'. There are a number of things going wrong with your truck. Try them in this order.

 

1) Go down to your local dealer and replace that little switch on the accumulator. This switch is a relay that allows your AC to blow cold. Bassically what it does is measure pressures and what not. DO NOT allow the dealer to install this part. If dealer installed you'll spend close to $150. The cost of the part should be about $12-$30 and anyone with a brain can install it. Originally this was all my truck needed and the air was cold as ice. This is most likely your problem especially if you said you jumped the switch and it didn't blow cold.

 

If this problem works and then all the sudden you begin to lose your cold air again this means your compressor probably has devloped a leak. Fortunatly for me I happen to be good friends with a gentlemen with expirence in AC and owns gauges. If you know someone like this have them check your compressor with these guagues, I don't remember off hand what is normal, but I'll try to post later on and let you know.

 

2) Replace compressor, condensor and O2 Orphus filter. This will cost you approx. $300 at a good auto parts store. This is what I'm having to do. Since your truck is a 95' it uses R134A coolant, which is MUCH less expensive than R12. This can be purchased for about $6 a can at any auto part store. You'll need 4 cans. This is about a $400 fix, if you can find a buddy with knowledge to help you do it and your kind enough to compensate him for his time.

 

Good Luck and hope this helps.

[beebow]

Thanks Mike, I'll let you know what happens. Our maintenance guy at work has A/C testing equipment so i'll see if I can get him to help me out with the refrigerant.