AC clutch pulley will not turn (1 Viewer)

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First, a Happy Thanksgiving to all. I give thanks to all who contribute on this site. I’m not a mechanic by even the loosest of definitions, but I’m crazy enough to try! Thanks to posts here I recently changed my power steering pump and shocks all the way around. I thought I was done for a while, not! I pulled in the garage after work yesterday and smoke was rolling out from under the hood. It was obvious where it was coming from...the AC compressor clutch/compressor. Today I had my son turn the engine over while I watched to see what the pulley and clutch were doing. The engine struggled and it was clear it wasn’t going to turn over. I took the belt off and it started right up. The pulley was frozen. Is there any chance it could just be the clutch or is it safe to assume that the compressor is toast as well? I don’t plan to tackle this myself as I have no experience or tools for AC work. However, I’d like to arm myself with some knowledge before I go to a new mechanic. One other note that may or may not be relevant. With the vehicle running, after removing the belt, I turned the AC on and I noticed a change in the sound of the engine. I turned it off, and again the sound of the engine changed. Again, there was no belt attached to the compressor pulley when I did this. I appreciate any time you may be able to spare!

Mike

Mike
 
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If the clutch is engaged and the compressor is not turning, the compressor is probably toast.
Depending on how it locked up, if it grenaded internally, you could be looking at a new condenser, dryer and expansion valve.
When the mechanic takes the compressor off the rig he/she should be able to look for and see if there are metal shavings in the high pressure line to the condenser. If there are no metal shavings you may be lucky and just need a new compressor and dryer (the dryer should be changed any time the system is opened.)
 

flintknapper

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Mike, you can test the compressor on the vehicle and get some idea what the issue is.

With the belt off....you should be able to freely spin the grooved portion of the pulley. It should not be locked up or gritty feeling in any way. It normally free 'wheels' until the A/C unit is turned on and calls for the magnetic clutch to 'lock up' to it.

IF the pulley DOES spin freely then move on to testing the compressor. They are NOT always locked up because of internal damage. Sometimes as a result of infrequent use...the half moon bearings on the swash plate simply bind up and they can often be dislodged by moving the compressor shaft both directions (forward and backward). IF you can not move the compressor either direction...then it is fair to assume internal damage.

The best way to grab the outermost part of the clutch is to use a 'locking oil filter wrench'. Just lock onto the outermost circumference of the clutch and try to rock it both directions. It will either free it up....or not. If not...then have your answer (its the compressor). You can pick up the tool at HB for $10.00

To answer your question about replacing only the clutch, Yes you can buy only that item....but it approaches the cost of a good 'reman' compressor....so most folks don't fool with it.

Turn Comp1.jpg


Turn Comp2.jpg
 
Joined
Nov 20, 2012
Messages
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If the clutch is engaged and the compressor is not turning, the compressor is probably toast.
Depending on how it locked up, if it grenaded internally, you could be looking at a new condenser, dryer and expansion valve.
When the mechanic takes the compressor off the rig he/she should be able to look for and see if there are metal shavings in the high pressure line to the condenser. If there are no metal shavings you may be lucky and just need a new compressor and dryer (the dryer should be changed any time the system is opened.)
Thank you!! Please forgive my ignorance, but I gather I should be able to look at the clutch and tell if it is engaged by its position. I gather that it is since the AC was on when it stopped working.
 

flintknapper

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Thank you!! Please forgive my ignorance, but I gather I should be able to look at the clutch and tell if it is engaged by its position. I gather that it is since the AC was on when it stopped working.

The clutch is electro-magnetic....so it only engages when a 12VDC power supply is applied.

When your engine is running the belt for the A/C compressor (goes from your crank pulley to the A/C compressor pulley) is turning the free wheeling pulley on the compressor. So it's turning any time your engine is on. When you select A/C at the dash, 12volts is sent to the Clutch Coil on the compressor and it electromagnetically pulls the clutch onto the drive face of the clutch pulley. The clutch is splined or keyed (depending on the style) to the compressor shaft....so the compressor becomes 'driven' at this point.

Below is a pic of the set up that is typical of ALL compressors (though the pulley is different in this case).

compressor-clutch.jpg


The clutch will normally 'engage' with a clicking sound if it working. Also, you can visually see it take up the 'air gap' (usually only .020") AND you'll see the compressor clutch itself begin turn (if it can).

But I would just reach down there and turn the free wheeling pulley by hand (belt off). That will tell you right away if the bearing in the pulley is seized (which might be your only problem). The bearing itself is replaceable. IF the pulley is good, then we move on to determine if the compressor is temporarily 'stuck' or if it worse (seized due to internal damage).

If you can get us this information....we are happy to help guide you the rest of the way as to what your options are.
 
Joined
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Messages
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Mike, you can test the compressor on the vehicle and get some idea what the issue is.

With the belt off....you should be able to freely spin the grooved portion of the pulley. It should not be locked up or gritty feeling in any way. It normally free 'wheels' until the A/C unit is turned on and calls for the magnetic clutch to 'lock up' to it.

IF the pulley DOES spin freely then move on to testing the compressor. They are NOT always locked up because of internal damage. Sometimes as a result of infrequent use...the half moon bearings on the swash plate simply bind up and they can often be dislodged by moving the compressor shaft both directions (forward and backward). IF you can not move the compressor either direction...then it is fair to assume internal damage.

The best way to grab the outermost part of the clutch is to use a 'locking oil filter wrench'. Just lock onto the outermost circumference of the clutch and try to rock it both directions. It will either free it up....or not. If not...then have your answer (its the compressor). You can pick up the tool at HB for $10.00

To answer your question about replacing only the clutch, Yes you can buy only that item....but it approaches the cost of a good 'reman' compressor....so most folks don't fool with it.

View attachment 2506923

View attachment 2506924

Wow! Sorry, somehow I missed this! So nice of you to lend a hand!! I will try turning it with said wrench, but it is not budging with my bare hands 😢.
 

flintknapper

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Wow! Sorry, somehow I missed this! So nice of you to lend a hand!! I will try turning it with said wrench, but it is not budging with my bare hands 😢.

If there is pressure in the system....you won't be able to turn the clutch by hand (or not easily) but you should be able to spin the pulley very easily. IF the pulley will not spin, then the bearing is shot at the very least. IF the pulley DOES spin but the clutch won't move (with the pliers) then you're looking at a new compressor.
 

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