How to test if A/C clutch is bad ??

[lone73]

The ac clutch on my '96 doesn't engage by itself all the time. When I turn on the a/c and it doesn't engage I can always pop it with my knuckle while its running and it will catch every time. The car has 201,000 miles on it, I assumed that my clutch was just so worn that the gap was getting too wide for the electromagnet inside to pull it in sometimes.

I have a new clutch coming in the morning...
Just wanted to get a sanity check that I am thinking right here and that the clutch is the culprit before I spend my money. ($192.00 at O-Reilly's)

Also, I've read that a/c clutches use shims in some cases. Is it possible that I could just shim it and get a few more miles out of it?

thanks
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[gmjunkie]

The ac clutch on my '96 doesn't engage by itself all the time. When I turn on the a/c and it doesn't engage I can always pop it with my knuckle while its running and it will catch every time. The car has 201,000 miles on it, I assumed that my clutch was just so worn that the gap was getting too wide for the electromagnet inside to pull it in sometimes.

I have a new clutch coming in the morning...
Just wanted to get a sanity check that I am thinking right here and that the clutch is the culprit before I spend my money. ($192.00 at O-Reilly's)

Also, I've read that a/c clutches use shims in some cases. Is it possible that I could just shim it and get a few more miles out of it?

thanks
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.
.

Why don't you remove a shim or two?? My guess there will be 5-6 in it! If there is no shims in it, it's time to replace it!! The New one will have to be shimmed also!

 

[ecss]

Here's a picture of the clutch assembly.

Gap between item #7 Pressure Plate and #3 Rotor should be .02 inches + or - .006 inches.

Also note the manual says you must discharge the system to replace the clutch assembly. Probably because of the way the manifold hose assembly comes across the front of the compressor.

I'm guessing you could just replace the Pressure Plate by itself if that's the problem with out discharging the system. I have heard some one say they bent the hoses for clearance and did not discharge the system. :ugh

The torque of the compressor shaft bolt item #1 is 10 ft. lbs.

 

[lone73]

Gap was definitely too big. I removed a shim and all seems well for now. Thanks Junk and ecss for the help and the diagram.
regards
lone73

 

[ct54531]

A/C Clutch ('84)

Does that graphic in your post, eccs, apply to 1984? I have no hose in front of the pressure plate so can this be disassembled "in place" withut discharge do you think?

 

[gmjunkie]

Does that graphic in your post, eccs, apply to 1984? I have no hose in front of the pressure plate so can this be disassembled "in place" withut discharge do you think?

Yepers!!!

 

[ct54531]

Holy Cow!! Talk about a brain fart. My car is an '87 not '84. (And I ought to know since I've owned it since new.) Anyway, the a/c worked fine last summer and fall (I'm in Florida). When I turned it on this year, no cool air. I checked the refrig level (R134) - it was low and I added brining it up to proper level. Still no cool air. Then I noticed the clutch not engaging (or disengaging? Out/in is what?) Fuse is OK. Is there a troubeshoot check list for this? Thanks.

 

[TWISTERUP]

Holy Cow!! Talk about a brain fart. My car is an '87 not '84. (And I ought to know since I've owned it since new.) Anyway, the a/c worked fine last summer and fall (I'm in Florida). When I turned it on this year, no cool air. I checked the refrig level (R134) - it was low and I added brining it up to proper level. Still no cool air. Then I noticed the clutch not engaging (or disengaging? Out/in is what?) Fuse is OK. Is there a troubeshoot check list for this? Thanks.

How are you sure you have a full charge if the AC clutch is not working? Do you have AC gauges ? BTW the clutch hub will move inwards (towards the compressor) when engaged.

 

[So Bay Vetter]

The ac clutch on my '96 doesn't engage by itself all the time. ..

Twisterup is right. The AC clutch on my 96 would not engage due to a small leak in my AC system (seal in the cycling switch).

 

[ct54531]

How are you sure you have a full charge if the AC clutch is not working? Do you have AC gauges ? BTW the clutch hub will move inwards (towards the compressor) when engaged.

Yesterday before posting, with the engine running and the A/C set to max, I took a pressure reading on the schrader valve on the top of the accumulator and got a reading of 45 psi. I just did the same - approximately 24 hours later: psi -35. I added more back up to 45. In either event, the air is not blowing cool - though the accumulator feels cool.
I think the clutch is engaged. Once in the past, with low level, it would click on and off a few seconds apart and my recollection is that disengaged it is visibly "out" from the body of the compressor. Right now, it's flush- whether the A/C is on or off.

 

[TWISTERUP]

Yesterday before posting, with the engine running and the A/C set to max, I took a pressure reading on the schrader valve on the top of the accumulator and got a reading of 45 psi. I just did the same - approximately 24 hours later: psi -35. I added more back up to 45. In either event, the air is not blowing cool - though the accumulator feels cool.
I think the clutch is engaged. Once in the past, with low level, it would click on and off a few seconds apart and my recollection is that disengaged it is visibly "out" from the body of the compressor. Right now, it's flush- whether the A/C is on or off.

When the engine is running and AC on ...if the part of the clutch hub all the way towards the front is turning then the compressor is in fact engaged. If this is correct and the system is not under charged OR overcharged the larger (suction side) of the 2 pipes/hoses at the compressor should be cold to the touch. If it is not "cold" I'd suspect it may be under charged IMO. At this point once again IMO....your best bet is to take it to someone capable of evacuating/pulling system into a vacuum and recharging w/the correct amount of R-134 and oil.

At this point if the pipe is "cold" and compressor is working it's possible that the temperature door inside the ac/heater box may not be working correctly. However once again be SURE the correct amount of R-134 is in the system before further diagnosis. That's my 2 cents

 

[minifridge1138]

How to tell if your AC clutch is working:
Disconnect the harness going to the clutch.
Attach 12V directly to the clutch.
This should cause the clutch to engage. If it does not, then it is not working.
You can do this with the car off. You should hear an audible click.

If you do not have 12V at the wiring harness (engine running, AC on), then the problem is some place else.

Find the low pressure cut-out switch.
Jump directly across the 2 terminals. This will fake a proper reading.
If the clutch engages, then you either are low on coolant or the pressure switch is bad.

Good Luck!!!