AC cycling on/off every 10 seconds. Normal?
Member
Joined: Feb 2005
Posts: 84
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Originally Posted by RamSS/T
I, like MANY others on the board, had the same problem. I added a can of "Sub-Zero" freon to it and it not only cycles far less but cools so much better. I checked it before I put the freon in and it was on the low side of acceptable pressure...now its toward the middle of the acceptable range.
My advice is to add a can of freon and see if that doesnt solve the problem.
My advice is to add a can of freon and see if that doesnt solve the problem.
What is the acceptable range? Is there a sticker in the engine compartment I am not seeing.
Technical Article Contributor
Joined: May 2004
Posts: 6,509
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From: Georgia on my mind...
Pressure gauges are not an accurate means to determine how much refrigerant is in the system. They'll give you a general idea of whether the system is undercharged or overcharged, and what the system is doing, but that's it. Pressures are best used as a diagnostic aid. The only way to determine how much refrigerant is in there and how low is it is to recover the refrigerant with a recycling station and weigh it. That said, no, rapid cycling isn't normal given ambient temps of 80-90 degrees or so or higher.
Senior Member
Joined: Mar 2001
Posts: 479
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From: Tallahassee, FL
my cycles on/off every 20 seconds or so under 96 degree conditions and stop and go traffic. but my meat thermometer in the vent is reading a solid 46 degrees so i know its not low on refrigerant.
Senior Member
Joined: Apr 2005
Posts: 491
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From: Mayflower, AR
My bro has a 2004 4.6. His A/C was not cold and they told him his front seal on the compressor was bad, so they replaced the compressor. Now his A/C blows at a downright frosty 58 degrees, max A/C setting. Obviously, this does not keep the truck comfortable here in Arkansas, where the temps are in the 90's-100's, and so is the humidity. They are still searching for the cure on his. My 05 does not seem to blow as cold as it should either, but I am seeing how they "fix" his first.
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Joined: Aug 2004
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From: Georgia
Originally Posted by mw1063
What is the acceptable range? Is there a sticker in the engine compartment I am not seeing.
The system holds 37 oz of R-134a. The A/C cycling switch opens at 21-23 psi and closes at 42 psi. Normal suction pressure range at 85 degrees outside air temperature and 30-60% relative humidity is between 37 and 57 psi. At 90 degrees, it's between 41 and 63 psi. Discharge pressures are 165-280 psi and 180-300 psi respectively. As you can see, it's not so simple to diagnose the system without the service manual charts and a set of gauges.