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New AC clutch slipping

miwitte on Sat July 16, 2011 3:36 PM User is offlineView users profile

Year: 2001
Make: Chrysler
Model: T&C
Engine Size: 3.8L
Refrigerant Type: R134a
Ambient Temp: 82
Pressure Low: 42
Pressure High: 180
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. There was also a knocking noise coming from the compressor. Once the knocking went away it ran smooth again the compressor on its way out? Today its 80 and its been running for 25 minutes at 42/180 and no noise everything looks ok. I am going to take it for a long drive and see how the pressures look. I am concerned the compressor is going, and thats what caused the clutch to separate

GM Tech on Sat July 16, 2011 3:49 PM User is offline

burnish the clutch 100 times-- turn it on and off- to break it in....

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......

iceman2555 on Sat July 16, 2011 5:20 PM User is offlineView users profile

Burnishing the clutch is an good should always be done fr a clutch replacement or compressor replacement. Turning the compressor on and off for 50-60 times.or do as GM states...100 times...fully charged system....engine RPM 1500. Use hi press/lo pressure switch to energize the clutch...turning it off and and on
However that being is highly suspect that your compressor is 'on the way' out. The knocking sound could be the result of lack of lube in the compressor....this resulted because of an lack of sufficient refrigerant to migrate the lube. The other could be excessive discharge pressures as a result of restrictions in the inlet side of the condenser. This is also the result of insufficient lubricant in the compressor and the resultant debris from that issue. If this is the case...the vehicle will require extensive repairs.
A good cheap test. Operate the vehicle for app 10 minutes....front and rear systems activated. Touch the discharge line (from compressor to condenser) if this line is extremely hot.....this is a very good indication of excessive discharge pressures as a result of the a restricted condenser.

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

miwitte on Sat July 23, 2011 10:25 AM User is offlineView users profile

So I tried the burnishings and that seemed to work as the temps have only been high 80's. This week temps near 100 and its starting again. Yesterday it was 100, and put gauges on it. At idle it was 70/250, it you bring it up to 2000 it would go to about 40/250. I drove it for a bit and the clutch would start slipping. I am thinking it could be a restriction and once it gets hot out its causing a issue because the high side cant go past 250. Should the low side be about 45-50 and high side about 300 when its 100 out? Seems like the high side wont go past 250ish.

It really hasn't been getting as cold as it should, also I know the charge is ok, as i had a leak over the winter that I repaired. It held a 29" vacuum overnight and I charged it to what the label said I think it was 44 oz.

I'll get gauges on when it slips.

mk378 on Sat July 23, 2011 11:19 AM User is offline

After you (presumably opened the system) and fixed the leak did you evacuate before charging? Air in the lines raises the pressures and makes for poor cooling and extra wear and tear on the clutch and compressor.

Is the port where you measure the high side before or after the condenser? If you're measuring after, a blockage in the condenser could make the actual pressure at the compressor much higher than 250.

Edited: Sat July 23, 2011 at 11:22 AM by mk378

miwitte on Sat July 23, 2011 1:33 PM User is offlineView users profile

Yes I have a nice robinaire that will pull 6 micron so I left that on for about 2 hours, then it held 29 inches of vacuum overnight. Charged with the specified amount from the label on the car. Its been running fine for over 6 months just 2 weeks ago the clutch started slipping and I replaced it and thats where I am. The high side is at the accumlator, and is on the output of the condensor. I will run it today and get some readings when it slips. Any specific RPM I should be doing this at?

miwitte on Sat July 23, 2011 2:09 PM User is offlineView users profile

So now the clutch just spins, gets hot and smokes. The rubber is melting and its spent. The compressor spins easily by hand.
1) So did i kill the clutch by not burnishing?
2) Is there a electical issue possibly and that there is not enought voltaget to fully engage(ill check that)
3) Since the original clutch appears to have died in the exact same fashion(melted the rubber and seperated) I am leaning to a compressor or blockage issue.

So do I spend $100 on another clutch or bite the bullet and replace the compressor for $300 plus the cost of a flush and recharge?

Its so frickin hot it will have to wait a bit i have a couple of other cars to drive so its not a big deal.

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