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Air conditioner compressor cycling too often?

2000 Chev Express van, 5.7 litre gas, front air only (rear air leaked and we just blocked off the whole rear section with caps and refilled the system). The compressor is noisy - but it always was noticable. It cycles on and off incessantly, exactly 6 seconds on, 4 seconds off. Problem is worse when the truck is under load (towing) and I am running in third gear at normal highway speeds so higher than normal RPM.

Any ideas? Air is cold, so it's working - but it sure doesn't seem normal. It seems to load the engine a lot as well, but that's probably my imagination.

Thanks, Brian

Reply to
Brian
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I'm thinking back to my two cars, and they both seem to cycle on for about 6 seconds or so on a steamy summer day in the mid-atlantic states.

As I remember the old style GM AC compressor would stay on consantly, but AFAIK that model isn't used any more.

You said the problem is worse when under a load, but I wasn't sure what you meant by worse. Are the cycles of shorter duration? Or is it just more noticable because the engine bogs a bit when the compressor kicks in.

Reply to
John S.

If I am driving under unloaded conditions - just cruising at 70 mph empty - the compressor cycles the same but is quieter. If higher rpm's it's noticably louder..

Brian

Reply to
Brian

If it is a noisy compressor to begin with, as some compressors are, it probably will sound even noiser at higher rpms.

Reply to
John S.

You are probably low on 134a. The low pressure switch turns the compressor off when it gets down to "X" psi. Once the compressor cuts off the pressures raises back up over "X" psi so the system turns back on. While I would reccomend having the low and high pressure sides checked to see how the charge is doing you can pick up one of those cans of 134a with the low pressure gauge built right on the can. They aren't the most accurate things in the world but will at least give you a clue if you are cutting off on low pressure.

Steve B.

Reply to
Steve B.

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