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post #1 of 4 (permalink) Old 10-05-11, 05:20 PM Thread Starter
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Arrow 2000 CV - AC Problems??

I have a 2000 CV LX and when the AC compressor comes on it works great and car is cold. The problem I notice is strange. When I am driving at 55 - 70 MPH and the compressor cycles I notice a slight vibration that willl only last for about 5 second. It happens only during the compressor cycling. When at lower speeds under 50 MPH you do not notice it happening.

The belt is tight. No sqeals coming from the compressor. Nothing appears strange. When not operating the AC no vibration. Is this normal for a older vehicle.

Need your feedback. THANKS

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post #2 of 4 (permalink) Old 10-05-11, 07:49 PM
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Re: 2000 CV - AC Problems??

The age shouldn't affect that. Mine doesn't. Try it at home with the A/C on and hold the throttle to a higher RPM and see if you acn see it under the hood to pin point the location.

Bert
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post #3 of 4 (permalink) Old 10-06-11, 01:35 AM
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Re: 2000 CV - AC Problems??

First, check the torque on your AC compressor, power steering, alternator and belt tensioner mounting bolts. Also check the alternator support bracket at the rear of the alternator for proper torque and cracks (check carefully, the cracks are hard to see). The most likely cause, however, is your serpentine belt tension. The belt tension spring looses it's "spring" over time and even though the belt feels tight, it is not within spec. The tension can be tested with a belt tension load tester, but I am not able to find the specs and I've never had much luck with their accuracy anyway. Does your belt show any unusual wear pattern?
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post #4 of 4 (permalink) Old 10-06-11, 09:10 AM
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Re: 2000 CV - AC Problems??

Tim:
I should expand on what I wrote early this morning. I wrote the text during a quick coffee break I took during an all night thrash (not a Ford this time, but a CRF450X) in the shop, and it was a little brief.
What you are possibly experiencing is called belt "wrap-up" Physics majors will be all over me, but I think the belt loads increase X RPMs squared. When the AC clutch engages at higher engine speeds, the belt is under tremendous load and it tries to "walk" or wrap, around the pulley. And it will if the tension is low, such as with a worn tension spring as I described in my first post. The vibration you are feeling are the oscillations caused as the belt, and any loose components driven by the belt, "un-wrap".
As Bert said, open the hood and see what's happening. Pay close attention to the idler pulley/tension pulley, then check for loose components.
Remember to never stand in line with any rotating belt or accessory while the eng is running.
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