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I’m trying to get the ac on my 90 GMC Sierra working, but the clutch isn’t working. I found this wire connected in the back of the ac compressor on top. Anyone know if I can bypass this or if I can even replace the plug without the compressor? The pin sticking out of the compressor moves around it is probably broken inside
I’m trying to get the ac on my 90 GMC Sierra working, but the clutch isn’t working. I found this wire connected in the back of the ac compressor on top. Anyone know if I can bypass this or if I can even replace the plug without the compressor? The pin sticking out of the compressor moves around it is probably broken inside
Looks like an R-4 Harrison A/C cutout switch to me.
Any idea if it can be replaced? The pin sticking out of the compressor is loose like it’s broken inside
Yes it can be replaced, but you would have to recycle the refrigerant, or vent it to Atmo, which is technically illegal, not that it happens all the time, with non-pro, shade-tree mechanics, since the chances of being caught are slim.
You could have a shop with the R-134A recycling machine depressurize your system, then do the work yourself, to be legal. The sensor is held in place with a snap ring and sealed with an "O"-ring. Some R-4 AC compressors came with an aluminum plug where your cut-out switch is. It might really be cheaper, in the long run, to dump your old unit and replace it with a re-manufactured or new unit, along with the receiver /dryer accumulator and the orifice tube, since your GMC is pretty old now.
Has your AC system been converted to use R-134A, not R-12 Freon? They should have attached a warning label to the vehicle if so, but the R-12 connectors screwed on, and the R-134A connectors are a push-snap design.I have converted a couple of old R4's Harrison's, using R-12 to use R-134A with very good results, and R-12 isn't available in the US anymore anyhow.
If you wish to only change the A/C cut-out sensor, you will need snap-ring pliers, and the new unit which is around $30 to 40 USD. You should put some A/C oil on the o-ring before you install it for a good tight seal and it makes it slide on in easier too. Then you'll need to evacuate all the air and condensation to Atmo using an A/C vacuum unit, which you may be able to rent, or you can buy one for about $100-150 dollars. Run it for at least half an hour or more when it's as warm out as it will get that day You should really dump the accumulator and orifice tube as they are pretty cheap, as well. Might want to add 2 ounces of A/C oil, to make sure you have enough oil.
Edit: BTW, have you checked your high and low A/C pressures at all yet? Looks like your switch has oil around it, so you might have a leak to contend with. The compressor uses switches, which will shut down the magnetic-clutch if pressures are not correct.
Last edited by oilcanhenry; Jun 7, 2019 at 4:14 AM.
Reason: Ask another question
Yes it can be replaced, but you would have to recycle the refrigerant, or vent it to Atmo, which is technically illegal, not that it happens all the time, with non-pro, shade-tree mechanics, since the chances of being caught are slim.
You could have a shop with the R-134A recycling machine depressurize your system, then do the work yourself, to be legal. The sensor is held in place with a snap ring and sealed with an "O"-ring. Some R-4 AC compressors came with an aluminum plug where your cut-out switch is. It might really be cheaper, in the long run, to dump your old unit and replace it with a re-manufactured or new unit, along with the receiver /dryer accumulator and the orifice tube, since your GMC is pretty old now.
Has your AC system been converted to use R-134A, not R-12 Freon? They should have attached a warning label to the vehicle if so, but the R-12 connectors screwed on, and the R-134A connectors are a push-snap design.I have converted a couple of old R4's Harrison's, using R-12 to use R-134A with very good results, and R-12 isn't available in the US anymore anyhow.
If you wish to only change the A/C cut-out sensor, you will need snap-ring pliers, and the new unit which is around $30 to 40 USD. You should put some A/C oil on the o-ring before you install it for a good tight seal and it makes it slide on in easier too. Then you'll need to evacuate all the air and condensation to Atmo using an A/C vacuum unit, which you may be able to rent, or you can buy one for about $100-150 dollars. Run it for at least half an hour or more when it's as warm out as it will get that day You should really dump the accumulator and orifice tube as they are pretty cheap, as well. Might want to add 2 ounces of A/C oil, to make sure you have enough oil.
Edit: BTW, have you checked your high and low A/C pressures at all yet? Looks like your switch has oil around it, so you might have a leak to contend with. The compressor uses switches, which will shut down the magnetic-clutch if pressures are not correct.
I was told it was converted already when I bought the truck. There are no warning labels or anything though. It has the new connector and I had checked the low pressure line it was empty. Haven’t checked the high pressure line. I don’t know much about a/c systems so I’m wondering if I should just take it to a shop. Thanks for all the info it was really helpful
I was told it was converted already when I bought the truck. There are no warning labels or anything though. It has the new connector and I had checked the low pressure line it was empty. Haven’t checked the high pressure line. I don’t know much about a/c systems so I’m wondering if I should just take it to a shop. Thanks for all the info it was really helpful
No problem. Thats why we automotive tech-heads are here.
Question about a wire
