A/c Not Working

bronyaur · March 25, 2008

The A/C on my '95 Suburban quit working. I noticed that the clutch wasn't engaging. I jumped the wires on a switch attached to the drier and the clutch works, so I assume the switch is bad. I checked the system pressure and it's a bit over specs, likely because the clutch isn't engaging. I'm no A/C mechanic in any way so I'd like to start with the easiest and least expensive thing, which at the present time looks to be the switch. What I need to know is the name of this switch and/or a GM part number, and I need to know if I can just unscrew the thing and replace it without losing pressure in the system. The switch has a part number on it and it appears to be 52468358, but part of it is blurred and I'm having to use a light and mirror to read it on the underside. Thanks in advance.

'95 Chevy Suburban K1500 5.7 w/ rear air

hubbycap · March 25, 2008

I think that is the low pressure cut out switch. It would definitly prevent compressor operation. Designed to keep compressor from running w/low refrigerant/oil.

ZZ327 · March 25, 2008

check the continuity across those 2 wires with a volt meter, Its a normally closed switch so if your voltmeter beeps its good.

I think you should be around 45 PSI engine RUNNING on your low side gauge.

bronyaur · March 25, 2008

check the continuity across those 2 wires with a volt meter, Its a normally closed switch so if your voltmeter beeps its good.

Easier said than done because the prongs on the switch are recessed back in there, but I checked it and there is no continuity. If the switch is supposed to be normally closed, then I would say it is stuck open, which helps confirm that the switch is bad. Thanks for the tip.

As for the pressure, with the engine running it was at 65. Once I get the compressor working I'll check it again.

bronyaur · March 26, 2008

Bump.

hubbycap · March 26, 2008

It is a pressure cut out switch and is a common aftermarket part. My compressor and dryer were changed out last year and it was not OEM. Check with just about any auto parts store ~$20-$25.

bronyaur · March 26, 2008

Okay I found the LPCO switch at Kragen for about $18 so I'll pick one up tomorrow. I'm assuming it can be replaced without losing system pressure, or I can do it fast enough without losing too much.

alaska511 · March 26, 2008

Okay I found the LPCO switch at Kragen for about $18 so I'll pick one up tomorrow. I'm assuming it can be replaced without losing system pressure, or I can do it fast enough without losing too much.

There is a schrader valve on your accumulator, you wont lose any when you change your switch.

hubbycap · March 26, 2008

Okay I found the LPCO switch at Kragen for about $18 so I'll pick one up tomorrow. I'm assuming it can be replaced without losing system pressure, or I can do it fast enough without losing too much.

I think it screws into a schrader valve. If it does you shouldn't lose any refrigerant.

bronyaur · March 26, 2008

Thanks for all the help. I'll post back when I'm done.

bronyaur · March 26, 2008

I installed the new LPCO switch and the A/C started working right away. I opened the doors and turned both the front and rear A/C to max, then attached a pressure gauge to the low side. I noticed that the clutch was cycling on and off about every 4 seconds. The pressure was running between 25 and 35. I added freon (almost a whole 19 oz. can) very slowly, and now it's cycling less but still cycling on and off every 8-10 seconds. I assume this is a problem, but what does it indicate?

ken1mod · March 26, 2008

It depends on temperature but that switch is there to cycle the compressor quite often. 8 to 10 seconds could be about right this time of the year. Is the aluminum cannister cold? It should be. You probably replaced a good switch because of low refrigerant level. It was still cheaper than going to a shop.

Ken

bronyaur · March 26, 2008

The switch was definitely bad as it was stuck open. There is no continuity through it, and the system did not work at all. Once I replaced the switch the system started working right away. The canister is cold, and I stopped adding freon when the low side pipe started to sweat. The temp here is in the high 50's. I'll keep an eye on everything to see how it works out. I'm hoping that constant cycling is normal as you suggest. Thanks for the feedback.

ZZ327 · March 27, 2008

its probably normal for it to cycle like that with those temps, usually 65-70 is a good time to start charging it up. You could try slowly filling it up until it takes longer between cycles. (I think my 05 cycles every 4-8 Mins) If you overcharge just let some out!