AC Issues - Wiring compressor clutch to a switch

Alex_M

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Hi all! I'm having issues with my AC system. I =recently replaced my AC compressor clutch. Worked good a few days then the coil melted out of the new clutch. I replaced it again yesterday and no cigar. No burnt fuses or anything, but it's not cycling on.

I'm on the road and don't want to take the time for a lengthy diagnosis right now. Is there any harm would come to the system if I just wire a switch to the clutch so it's on/off? It wouldn't cycle, but I don't see that hurting anything I can think of, however Id like some more experienced opinions.

Thanks!
 

UmmScott

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Stop just replacing the clutch. Thats a waste of time.

All there is to it.
You get 12 volts to engage the clutch. Unless you have some sort of crazy erratic on/off (which you would most definitely hear and notice with poor ac performance), then the clutch is/was probably fine and something else is taking it out.

Other things to check. Ground side and the diode.
There is a 1 way diode and electrical current is supposed to go 1 way thru the clutch.
If the ground is poor/weak, that'll give you a low voltage condition and the clutch will burn up like you said.
Check your ground connections carefully.
Wiring diagram will help here.
 

Fjs0001

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Maybe your pressure switch is faulty or you need more refrigerant. You can bypass the senor by putting a paper clip in the sensor connector.
 

Scottydoggs

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might burn up the compressor. the high pressure switch tells the clutch to turn on, if its low or broken, it wont turn the compressor on. green wire is the one that gives power to the clutch.
 

Alex_M

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Stop just replacing the clutch. Thats a waste of time.

All there is to it.
You get 12 volts to engage the clutch. Unless you have some sort of crazy erratic on/off (which you would most definitely hear and notice with poor ac performance), then the clutch is/was probably fine and something else is taking it out.

Other things to check. Ground side and the diode.
There is a 1 way diode and electrical current is supposed to go 1 way thru the clutch.
If the ground is poor/weak, that'll give you a low voltage condition and the clutch will burn up like you said.
Check your ground connections carefully.
Wiring diagram will help here.

Clutch definitely needed replaced both times, but at this point I think it's fairly conclusive that there is a further issue than just "the truck has 300k miles on it".

Is the diode internal? I'll pull out the meter and do some poking around. Luckily(?) It's been pretty cold since I made this post initially, so we haven't needed the AC since.

Thanks!

Maybe your pressure switch is faulty or you need more refrigerant. You can bypass the senor by putting a paper clip in the sensor connector.

I'll try bypassing the switch first to see if it at least cuts on. Thanks!

might burn up the compressor. the high pressure switch tells the clutch to turn on, if its low or broken, it wont turn the compressor on. green wire is the one that gives power to the clutch.

Green wire, got it. I'll check it. Thanks!
 

UmmScott

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The most important thing you need to do here is verify you're getting actual running voltage 13.5 to 15.3volts to the clutch.
Like the other guys said, theres a clutch cycling switch on/near the accumulator and a high pressure safety on the compressor or on the discharge line..

Over time these can become erratic and you'll have voltage drops across them which will make your clutch voltage low and overamp. Generally the fuse will blow before that happens tho.
Also your clutch relay check that as well.
Make sure your ac clutch fuse is the right size and someone didnt put in a larger one.
Wayyy easier and convenient to keep replacing fuses versus replacing the clutch
 

Alex_M

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All right fellas, we're headed back into lower elevations today so I did a bit of poking around.

I did find a blown fuse I missed. Replaced that and it worked for about 2 minutes. The fuse did not blow again and I swapped relays with the horn relay. Still no cigar.

I pulled the meter out and confirmed 14v at the connector while the truck is running, but the clutch is back to not engaging.

Back on the road. May poke around again at the next stop.
 

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