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Intermittent AC Problem

Old Jul 11, 2010 | 05:20 PM
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Intermittent AC Problem

Went on a 400 mile trip to the inlaws and back this weekend, having some intermittent AC problems.

First start the truck up, AC works fine, cruise at 80 with cruise on, its fine.

Get into stop and go traffic, and the compressor disengages. Start going, and between 1300 and 1700 rpms, can feel the compressor kick in and ac is great again. Can kind of half hear the compressor go, but feel it in steering wheel as well since it hesitates the PS pump I think.

Did a visual, connections seem tight, but I don't know squat about AC systems, any ideas on where to start?

Thanks

Also, this is really the first the AC has been used since last September, not a ton of call for it in MT.
 
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Old Jul 11, 2010 | 05:49 PM
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may be time for a new belt if you feel it in the steering wheel..a hard dry belt from age will slip..
 
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Old Jul 11, 2010 | 05:56 PM
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Belt

Ron,

Belt is 15 months old, about 18000 miles on it. Just went out and took a peak at it, no cracks, soft and pretty supple when i turn on it. Started truck, no slipping type sounds, but could hear the compressor engage/disengage several times.

Is there some sort of sensor or selenoid on that thing that could be sending erratic signals? like I said in the original post, I don't know anything about AC units for the most part.

Thanks for the help, keep it coming
 
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Old Jul 11, 2010 | 06:00 PM
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in that case i would get a gauge on the AC to see if she is full..wal mart has that and the freeon..
 
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Old Jul 11, 2010 | 06:01 PM
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In traffic, you are not getting enough air flow through the condenser, the a/c compressor is building up a high head pressure, and loading up the a/c comp putting a heaver load on it, the high pressure switch is kicking on and off the a/c compressor, your fan clutch may be defective, not drawing in enough air, you could add some electric cooling fans in front of the a/c condenser to aid in cooling the condenser, blow out the radiator and condenser with compressed air, hope that helps, Chellie
 
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Old Jul 11, 2010 | 06:31 PM
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Intermittently working? Take a look here:
SpringerPop's Compressor Clutch Air Gap

When they get intermittent, there's a reason.

Pop
 
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Old Jul 11, 2010 | 06:39 PM
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Thanks!

Thanks to all that replied, now I have somewhere to start. Took a look at my AC condensor, its in decent shape, not too many smashed fins or bugs, and its only bee 80 or so, and I was running empty.

Pop, I am going to dig out my feelers gauges as soon as I get the fence fixed the horses so kindly broke while I was out of town. Will let you know soon.
 
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Old Jul 11, 2010 | 06:45 PM
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I had the same problem. I checked the air gap first, checked the freon next, then finally got around to replacing the clutch. Blows cold at idle now in the warm Texas sun.
 
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Old Jul 11, 2010 | 06:47 PM
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The clutch air gap is a good thing to check for, but as you mentioned, the problem does not happen at cruise speeds of up to 80 miles per hour, just in traffic, where there is little air flow.
 
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Old Jul 11, 2010 | 07:17 PM
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Tom, I did Pops trick on two trucks so far and it fixed the problem.
both times.
Hope thats all it is for ya, its a simple fix.
Good luck.
 
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Old Jul 11, 2010 | 07:27 PM
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Originally Posted by ron's power stroke
in that case i would get a gauge on the AC to see if she is full..wal mart has that and the freeon..
The cheap low pressure gauges are useless except to see if there is any refrigerant in it. It needs a real gauge set put on it to check pressures.
 
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Old Jul 11, 2010 | 07:38 PM
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.060

We are at .060 right now, so that is my first step. Thanks for all the responses, right now its air gap, then gauges, then a clutch. Air gap is free, so thats tomorrow nights project, thanks all.
 
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Old Jul 23, 2010 | 07:22 PM
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Thanks everyone for the answered OneLionHunter. Thanks to Springerpop for the tutorial. I fixed my intermitent AC, or atleast I think I did, had about a 0.055 gap and a 0.035 shim when i took it apart. Removed the shim and could just squeeze the 0.020 feeler into the air gap. Fired up the truck with the AC off, clutch was disengaged, turned AC, AC engaged, turned it off and it was diseneged. Now the real test will be my ~60 mile trip tomorrow morning and then tomorrow evening back home.

My AC would work fine when I was driving, but if I came to a stop it would continue to work until I went to take off again (never gental on the gas). If I left it off for a while it would work again a little later when I turned it on.

Chris
 
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Old Jul 24, 2010 | 03:26 AM
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i have this exact problem, i am so happy this thread is here!
 
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Old Jul 24, 2010 | 08:03 AM
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Mine started to become intermittent about a month ago. Truck has 318xxx miles. Only problem ever was the wire connector to the comp. I took out a .034 shim but I really think mine maybe wore out now!


Question can the clutches be replaced without removing the compressor?
 
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