new AC clutch slipping

miwitte on Mon August 08, 2011 8:49 AM

Year: 2001
Make: Chrysler
Model: Town and Country
Engine Size: 3.8L
Refrigerant Type: R-134a
Ambient Temp: 95
Pressure Low: 55
Pressure High: 250
Country of Origin: United States

wives minivan had the clutch hub completely go, the rubber ring connecting the clutch plate and the inner hub became separated. I replaced it with a new clutch, solenoid, pulley, checked and adj air gap to spec, changed serpentine belt everything went smooth. Started back up and after a while once the pressure got up to 55/250 (95 degree day) the clutch seemed to start slipping. Now looks like it got so hot its starting to melt the rubber and the clutch is completely slipping cannot build any pressure. The a/c can be turned easily by hand so the compressor is not seized.

So here are my thoughts;
1) When I installed it I did not burnish the clutch, found out about that here.
2) The air gap was extremely hard to set, the hub of the pulley is in the way. I bent a feeler gauge to try and slip in, not sure how good of a job I did.
3) The initial failure was exactly the same as the second time. A/C has worked great, in fact we took a 12 hour trip in 95 degree heat a week before the issue and A/C was fine.
4) i tested the voltage to the clutch and its 13.8V with the clutch engaged.
5) the new clutch failed within maybe 10 miles of driving.

So my questions are
1)Was the initial failure just the clutch getting old, then getting hot, then the rubber connecting the clutch and the inner hub separate. Or was it the there is a mechanical issue with the compressor that made the compressor harder to turn than the clutch can handle?
2) was the 2nd failure because i didn't burnish or have the air gap set correctly or was it still a mechanical issue with the compressor?
3) Should i buy a new clutch again for $70 and try again?
4) what other things can I verify and make sure of so i don't burn it out again?

Before I replace the compressor, I think another clutch would be a good idea to try, just want to make sure I do it right so any suggestions would be welcome.

Thanks!!

iceman2555 on Mon August 08, 2011 9:57 AM

Appears that there is a pressure lock of the compressor. Nothing was mentioned about preparing the system for a new compressor...simply the installation of a new unit...! If the system was not serviced properly, flush, lube, recharge....these could be concerns...but the first idea in my old mind is the condenser. Since the compressor rotates by hand...not a mechanical lock up.....voltage seems to be adequate...although a voltage drop test would be in order....knowing the vehicle and past problems....the condenser more than likely the problem.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

GM Tech on Mon August 08, 2011 10:28 AM

You replaced only the clutch driver - right?

Then pulley face is probably "work hardened" from being burnt and now new clutch driver has to try to mate with hardened blued steel---

you did not mention if cooling fans are working properly--- high head pressure can aggravate a vulnerable clutch....clutches (pulley and driver) are best replaced in pairs- if you go with a used unit, always get both the pulley and driver. Since they have been "worn in" together.

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

miwitte on Mon August 08, 2011 10:42 AM

This was not a new compressor, only a new clutch, hub coil bearing etc. I think it may be because I didnt properly gap and didnt burnish...

mk378 on Mon August 08, 2011 11:16 AM

If there's ever a doubt about the gap, make it smaller. There's no such thing as too close until you get to where it rattles or drags when off.

miwitte on Mon August 08, 2011 3:51 PM