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Need help with S10 AC Relay!!

bnb1023 on Tue July 31, 2007 7:48 AM User is offline

Year: 1996
Make: Chev
Model: S10
Engine Size: V6

My AC compressor will not come on. I checked the fuse, and it is ok. Since the system was replaced last year, I am assuming that I might have a relay problem. The Chilton book shows 4 relays on the firewall. How do I get them off, and how do I test them? Can Autozone do it? What do they cost. I've had no real answers from other forums. HELP!!!!

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96 S10 4X4

GM Tech on Tue July 31, 2007 8:15 AM User is offline

The numbers state from my vast database-- that 65% of a/c inops are due to loss of charge, less than 10% are compressor failures- about another 15% are electrical problems- of which the relay is about 3% of that-- so why do you want to go with only a 3% probability as your first guess? Go with the loss of charge as your first guess-- jumper the cycling switch connector on the accumulator- this will tell you that you most likely have a low charge- also check with a gage set what the static pressure is to confirm-- about 20% come to me dead flat-- absolutely no refrigerant in them- just because it has been serviced doesn't mean it hasn't lost refrigerant.............I can't remember ever servicing an a/c relay on an S-10................

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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......

graeme on Tue July 31, 2007 11:57 AM User is offline

Quote
Originally posted by: bnb1023
Since the system was replaced last year, I am assuming that I might have a relay problem. !!!!
What was replaced? everything? compressor,evaporator, condensor etc? Dont know the specifics of the wiring in your vehicle, but would check with a voltmeter where exactly you are getting power to (given that you most likely dont have gauges to check for any pressure in the system).
If there is 12V at the compressor and it doesnt appear to be engaging then perhaps a clutch prob
If no voltage at the compressor, work your way backwards to the cut off/high/low pressure switch: check to see whether there is 12V here. If only on one side of the switch then either a charge prob or switch is faulty.
If no voltage on either side of the switch work backwards further........possibly this will lead you to your relay bank.......apparently only a 3% chance you will get this far!

bnb1023 on Tue July 31, 2007 11:59 AM User is offline

Thanks for the reply. Actually, everything was REPLACED a year or so ago, so that is why I do not think it is a low refrigerant problem. But it may be, so I will check. But, HOW do you get the relays off? I'm afraid to pull too hard. And, of the four, do you know which one is connected with the compressor? Thanks.

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96 S10 4X4

NickD on Tue July 31, 2007 12:18 PM User is offline

Don't have a circuit for your 96, but on a couple of years older, the S-10 did not even use a relay, was fed directly by the low cycling switch in series with the high pressure switch that got it's 12 V from the climate control panel from the ignition switch. Super simple.

Are you sure you even have a clutch relay? GMTech is suggesting you get some manifold gauges and post pressures at 1,500 rpm, AC on, blower at max, and tell what the outside temperature is.

bnb1023 on Thu August 02, 2007 8:09 AM User is offline

Chilton's says there are four on the firewall, and shows a picture. It also says that it is could be a good reason the compressor is not kicking on, in the troubleshooting section. Indeed, there are four square things that look like electrical somethings on the firewall. How do you get them off without breaking them, for testing. That's all I want to know for now. Thanks.

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96 S10 4X4

GM Tech on Thu August 02, 2007 10:07 AM User is offline

Slip a .020" shim (or a very thin flat bladed screwdriver) in the bracket behind them- to release the latch- then pull up on the relay- very simple- it is the relay with the pink wire and other wires are green. Chiltons manuals are nearly useless BTW........

-------------------------
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......

parollback on Thu August 02, 2007 2:34 PM User is offline

I have a '98 S-10 and I had the same problem with the system not cycling and it was due to a low charge. I did exactly as GM Tech explained (jumping the cycling switch on the accumulator) and the compressor kicked on. After putting my gauge set on and confirming very low pressure, I recharged it and it works fine. I believe the compressors are known to leak on those vehicles, as mine has dye and oil around the compressor.

revdrw on Thu June 18, 2015 3:33 PM User is offlineView users profile

Is that the same for a 94 S-10? How can you jump the relay?

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Just a simple man trying to make wise choices.

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