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Does anyone know how long the A/C compressor cycle period should be? After hearing the "clunk" or "thump" noise all the time on my 2006 LLY I popped the hood to look at the compressor. The engagement is really smooth but I had it on Auto 72 degrees and it would cycle about 5 seconds on and 10 seconds off, it was about 70 degrees outside. I then cranked it down to 60 degrees and it cycled somewhat longer but then would turn off for a wait period. I figured it would just stay on for a while kind of like a home air conditioner does until it gets down to temperature in the cab. Is this normal operation? Seems to blow cold air but until temps get back up to 80-90-100 degrees I may not know.

Thanks,
Bill.
 

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Sounds normal.
 

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Does anyone know how long the A/C compressor cycle period should be?
It will vary with the outside temp, and the amount of charge in the system. Sounds ok, I wouldn't worry to much.
 

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westdrz;1569377; said:
Does anyone know how long the A/C compressor cycle period should be? After hearing the "clunk" or "thump" noise all the time on my 2006 LLY I popped the hood to look at the compressor. The engagement is really smooth but I had it on Auto 72 degrees and it would cycle about 5 seconds on and 10 seconds off, it was about 70 degrees outside. I then cranked it down to 60 degrees and it cycled somewhat longer but then would turn off for a wait period. I figured it would just stay on for a while kind of like a home air conditioner does until it gets down to temperature in the cab. Is this normal operation? Seems to blow cold air but until temps get back up to 80-90-100 degrees I may not know.

Thanks,
Bill.
Its not a timed cycle its cycles on high pressre, low pressure,coil freeze control and temperature. Asyou said wait till it warms up and you'll know quickly.
 

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depends...

the ac cycle also depends on the humidity in the air, if it is more humid- the compressor will run longer, rather than a dry day.
 

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Do you have it on defrost? When the defroster is on there is a very audible "thump". I think it's just the little vent doors closing and opening. Turn the XM up!
 

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My A/C cycles just like this unless it is on max or I call for a big difference in cabin temp versus actual temp. I would call it normal, same as these guys.
 

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i get a thump from my compressor. it is the compressor as that is where the sound is coming from. i am going to have the dealer, vaccuum the system and recharge it. i had this issue before in my lly due to an air bubble in the system. once, i sucked the system down and recharged it, all was well.
 

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072500hd LBZ 3000mi. I have noticed a thumping sound every so often coming from passenger side. You can feel it too. No rym or reason but doesnt seem to do it when on the trottle just when you let off and slowing down. Any opinions?
 

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I've had the same exact thump in my 07' Classic GMC. I stopped by the stealer. They said, "keep an eye on it" and that they would look at it when I got my free oil change with them (the one and only time they will do my oil). The look on his face said it all...he didn't know anything.

The thumping however was every 30 seconds. I can't say it does it all the time but when it does...I can set my watch by it. Sounds like some guys here are accepting this as normal. My question is if there is a problem with the factory filling these systems improperly putting air inside or something of the like. Kinda like them being 14-20 oz. short in our rear differentials?:rolleyes:
 
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