A/C help needed

[heavymetalmachine]

Again K2500 350 auto.......

Now that I got rid of the rattles I'm ready to fix the A/C...

Looking over the web I have decided to replace the o-rings, dryer, compressor seals, orifice, etc.

Now when I hit the A/C button I get nothing the clutch does not kick in. I don't have any A/C codes flashing.. The parts tuck I have the compressor worked at least the clutch locked up so I thought I would swap.The one in the 1990 has two plugs going into it while the one on the 92 only seems to have one..

Can they be interchanged????

Is it possible for me to swap out the clutch from one to the other??


Thanks..............

[kokopelli85]

i'm not 100% on the early 90's stuff but i know my 97 has a low pressure shut off relay or somethin on it that disengages the clutch... it begins turning the pump on and off in like ten second intervals when the pressure starts to get low and when the pressure gets too low it will just keep it off to prevent damage. any way, once it does that you gotta get the presuure up to like 150 a couple people said b4 it will kick back on. this doesn't always work though and most people say to jump the relay with a paper clip to turn it on while you refill the freon. i had to jump mine off personally and my a/c works great now. hope this helps.

[heavymetalmachine]

Thanks for the reply...

Can you elaborate on jump the relay with a paper clip??????

[jdmccright]

You should be able to cross-check the part numbers from each compressor to verify compatibility, but off-hand they should be the same. The clutches can be removed, but unless you've done it before and have the tools you might just take them to a shop and pay $50 to do the swap as it needs to be pressed on the compressor shaft.

I tried it once, bought the little tool, got the bad one off, but it failed going back on. Paying the guy would've saved me alot of time and hassle. Hope you have better luck than me.

The low pressure switch is located in the line next to the condenser in front of the radiator. Disconnect and use a piece of wire to short the contacts just to check for clutch and compressor operation...do not run it like this for long.

First make sure there is refrigerant in the system by using a A/C gauge set. If it is low, you can recharge with a can that has a leak detection dye to see where the leak is. If it is zero, you should evacuate the system first with a vacuum pump to remove any water accumulation, then proceed with the referigerant/dye charge.

Hope this helps!

[heavymetalmachine]

Ok I just got done and as of now I have nice cold ac.....

As I was replacing the o rings I found one on the compressor that looked to have failed..The dyer went in with no trouble as did the orifice tube..I did however have to jump the switch to keep the clutch engaged as I filled it up...

Thanks again for all your help....

[heavymetalmachine]

Ok it all leaked out....

The only thing i did not change are the valve stems...O'Reillys cant sell me the tool I need to remove..They did sell me a tire tool that did not work....

Any ideas of what to do next??Some dye maybe???

[jdmccright]

If you have a small, throw-away flathead screwdriver you can do what I did and make your own valve core tool. Just cut a wide, deep notch in the blade with a Dremel tool (go carefully so you don't break the cutter blade). Takes a steady hand and/or a bench vise, but it sure beats that tiny, stubby tool you usually get.

I did suggest recharging with dye earlier, but leaks from the valves are usually audible with the engine off...as soon as you loosen the caps you hear a "hiss" sound, even if only for a moment.

Some GM trucks have a flat ball-style valve on the high-side line instead of the schrader-style that are prone to leak. This can be replaced with a valve from a R134a conversion kit. It's actually cheaper to buy the retro kit than a new ball-style valve. The fitting can be simply unscrewed to replace it once the system is discharged.

Keep trying and good luck!