A/C Compressor cycling issues
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Tuned
Joined: Jan 2009
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From: Carmichael, CA
A/C Compressor cycling issues
My truck has aftermarket r134-a setup. Anyways, the high-low pressure switch was leaking so I went and bought a new one had it replaced and the system recharged. I drove off with the A/c working until the next day when I was driving I could hear the compressors clutch cycling on and off as I drove. Anyways, as of yesterday I decided to give the air a try and It took approximately 10 minutes to get cold but it stayed on for 10 minutes blowing colder air than the 90 degree heat outside which is amazing. Then when I got up to a turn signal the clutch disengaged again and continued failing to disengage. What else could be the issue? The clutch cycle switch?..which appears to be almost brand new. I have a six month old baby and NEED A/C because it's hot.
New User
Joined: Oct 2006
Posts: 8
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From: Browns Mills, NJ
I actually just spent the weekend getting my old R-12 system working on R-134A after not using the R-12 system for over 3 years due to my compressor seizing up. Blows nice and cool now.
Anyways this sounds like a classic case of being low on refrigerent. Easy way to find out is to get one of those bottles from autozoo with the filler, turn your A/C on full and put the fill bottle on the service port on the low pressure side, the one on the accumilator/dryer on the pass side. Normally the reason it switches on and off is when the low pressure rises, it triggers the switch and then when it all moves to the high side it goes off.
Best way to fill it is to jump the switch with a paperclip or a wire so the compressor keeps running and service the low pressure side as directed untill the pressure stays steady, the dructs are blowing cold air, and your compressor no longer cycles.
Hope this helps!
Nick
Anyways this sounds like a classic case of being low on refrigerent. Easy way to find out is to get one of those bottles from autozoo with the filler, turn your A/C on full and put the fill bottle on the service port on the low pressure side, the one on the accumilator/dryer on the pass side. Normally the reason it switches on and off is when the low pressure rises, it triggers the switch and then when it all moves to the high side it goes off.
Best way to fill it is to jump the switch with a paperclip or a wire so the compressor keeps running and service the low pressure side as directed untill the pressure stays steady, the dructs are blowing cold air, and your compressor no longer cycles.
Hope this helps!
Nick
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Tuned
Joined: Jan 2009
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From: Carmichael, CA
It's in the caution yellow zone a little, but I thought that since it's older that they need higher amount of freon? Anyways the people at the shop filled it. Ive delt with the thing cycling on and off for the longest time and assumed it was because of the leaky low high pressure switch. But i guess not?
New User
Joined: Oct 2006
Posts: 8
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From: Browns Mills, NJ
R134A compresses at a higher temperature so you should actually need less of that than R12, but that gauge is designed for R134A. The compressor must be running for you to take your measurement because that is when the switch turns it off.
You could have a leak causing it to lower the amount in your system.
Also, was the system flushed and the orifice tube changed? Mine was 100% clogged with gunk, could barely pull it out of the tube.
You could have a leak causing it to lower the amount in your system.
Also, was the system flushed and the orifice tube changed? Mine was 100% clogged with gunk, could barely pull it out of the tube.
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Joined: Sep 2005
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When i try to recharge my system the guage on the LP side (part of charge kit) drops to ~20psi then the compressor kicks out. It only engages for about 2 seconds then it's back off. Where is the LP switch you mentioned above to jump and keep the compressor on? Do you think this is the problem? I'd appreciate any advice or suggestions!!
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Fleet Owner
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From: Kentucky
The clutch should cycle on/off as part of it's normal operation. It is controlled by the clutch cycling switch located on the side of the accumulator. In high ambient temperatures/humidity the clutch will stay engaged for longer periods of time. The clutch switch normally opens at ~20 PSI and re-engages around 40-45 PSI. 65-70 PSI on the low side is way too high. The pressure should drop the longer the clutch is engaged.
Without knowing how much R-134a they put in by weight it is going to be difficult to determine if it is overfilled or there is a restriction. You really need to determine what the high side pressure is as well as monitor the low side. That means using a manifold gauge set to watch both at the same time. If both sides are high, it is probably overcharged. If only the low side is high it could be a clogged orifice tube or if the pressure is fluctuating a bad compressor. It might be time to invest in a manifold gauge set.
Without knowing how much R-134a they put in by weight it is going to be difficult to determine if it is overfilled or there is a restriction. You really need to determine what the high side pressure is as well as monitor the low side. That means using a manifold gauge set to watch both at the same time. If both sides are high, it is probably overcharged. If only the low side is high it could be a clogged orifice tube or if the pressure is fluctuating a bad compressor. It might be time to invest in a manifold gauge set.
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Thanks for all the info. After a little more trial and error and additional assistance I finally figured out that even though I had peirced the bottle the refrigerant wasn't flowing from the bottle. Backed off the gauge assembly a 1/4 turn and the gauge on the fill kit pegged out for the first time. Once that was resolved it charged right up. Set the low side to ~45psi with the compressor engaged. It's about 85 deg here so I think thats about right. Thanks again for the help!!
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