A/C trouble-shooting
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Joined: Aug 2005
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From: State College, PA
A/C trouble-shooting
Hi all,
My A/C compressor/clutch have started making really bad howling noises. How do I determine if it is the clutch or the compressor? Here is the chain of events: turned on the A/C and used for 10 min and worked fine, shut off A/C for 20 min, turned A/C back on and no/reduced cooling but not hot either, 10 min later after several on/off cycles with the switch it started to cool again, this was all at highway speed so I did not hear any thing unusual, then at town speed I heard the noises. Shut the truck and A/C off for a couple of hours then restarted and it still is making some noise. If it is the clutch I will do myself, if it is the compressor I will have to take it to a mechanic because I do not have the required A/C tools.
Thanks,
Chris
'97 F250 LD 4.6L
My A/C compressor/clutch have started making really bad howling noises. How do I determine if it is the clutch or the compressor? Here is the chain of events: turned on the A/C and used for 10 min and worked fine, shut off A/C for 20 min, turned A/C back on and no/reduced cooling but not hot either, 10 min later after several on/off cycles with the switch it started to cool again, this was all at highway speed so I did not hear any thing unusual, then at town speed I heard the noises. Shut the truck and A/C off for a couple of hours then restarted and it still is making some noise. If it is the clutch I will do myself, if it is the compressor I will have to take it to a mechanic because I do not have the required A/C tools.
Thanks,
Chris
'97 F250 LD 4.6L
Senior Member
Joined: Oct 2002
Posts: 7,295
Likes: 125
From: St. Louis (Out in the woods)
If it is the clutch only, it may still make the noise with the A/C switched off if the problem is the pulley bearing. However, if the clutch friction/plate is slipping, it will only make the problem noise if the clutch is engaged.
If the compressor is seizing due to internal failure or excessive drag, it can cause the noise only when the clutch is engaged and the clutch is taking a beating.
Best way to try to pinpoint it is to remove the serpentine belt and see how much torque it takes to rotate the compressor shaft (use the bolt head on the clutch side). If the compressor is failing internally, you'll either have to apply excessive torque or you will feel rough spots in the rotation of the shaft or wil hear slight noises. The service manual only gives a torque value of 7 lb-ft for a discharged system, it doesn't give a value for checking it in-vehicle with a full charge. If testing it this way, you should be able to feel (and measure) the fluctuations in torque as the reed valves open and close. You'd be looking for a noise or a sharp bind feeling when checking this, anyway.
Based solely on your description, I'd slightly lean to the clutch as your only problem. The torque check can help pinpoint the fault.
Steve
If the compressor is seizing due to internal failure or excessive drag, it can cause the noise only when the clutch is engaged and the clutch is taking a beating.
Best way to try to pinpoint it is to remove the serpentine belt and see how much torque it takes to rotate the compressor shaft (use the bolt head on the clutch side). If the compressor is failing internally, you'll either have to apply excessive torque or you will feel rough spots in the rotation of the shaft or wil hear slight noises. The service manual only gives a torque value of 7 lb-ft for a discharged system, it doesn't give a value for checking it in-vehicle with a full charge. If testing it this way, you should be able to feel (and measure) the fluctuations in torque as the reed valves open and close. You'd be looking for a noise or a sharp bind feeling when checking this, anyway.
Based solely on your description, I'd slightly lean to the clutch as your only problem. The torque check can help pinpoint the fault.
Steve
Senior Member
Joined: Nov 2006
Posts: 5,495
Likes: 7
From: Memphis, TN 38135, USA, Earth
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