A/C cycles on and off

dbeckwith · Post by **dbeckwith** » 14 May 2011, 09:38

Aside from freon level and gap of compressor clutch what else could be the culprit causing it to cycle of and off every few seconds. The clutch kicks in so I don't believe the gap is the problem and the freon level is approx 35# and I just added another can just because. Is there a sensor or something that could be causing this issue?

Post by **jblackburn** » 14 May 2011, 10:11

What temp is it outside?

dbeckwith · Post by **dbeckwith** » 14 May 2011, 11:34

About 80

Post by **jblackburn** » 14 May 2011, 11:38

With the compressor running is it pulling it down below 25 psi and then clicking out again? Around 80 it should be maintaining a charge of around 40 psi consistently - if it pulls it down and then cycles off, it is still low on R134

dbeckwith · Post by **dbeckwith** » 14 May 2011, 11:46

Yes that is pretty much what is happening. It will pull it down to 25 or so and then kick out. I thought since the system was holding 25 pounds or so I could feel confident that the system doesn't leak. Although I am not sure of the maintenance before 2 years ago I know my step-daughter did nothingto it in the past 2 years. That is the main reason I confiscated it from her. One time she ran it without water, another she came home with smoke pouring out from hood, and another time she didn't even make it home and then I am left to pick up the pieces, so I have been putzing with it the past couple of weeks. this week it is the air conditioning. Next week maybe the timing belt.

Post by **jblackburn** » 14 May 2011, 13:32

Most of these cars leak a small amount but will still hold a charge for a few weeks/months; the AC evaporator is a known weak point in the system.

Your best bet is to charge it up (the back of the can will have recommended pressures based on the outside temperature - it should hold around 35-40 psi consistently with the compressor running) and see how long it will hold a charge before it's back to the point where it starts cycling in and out again.

dbeckwith · Post by **dbeckwith** » 14 May 2011, 13:53

OK, thanks for your response. I'll do it tomorrow. We are under severe thunderstorm warnings right now

busyangel1 · Post by **busyangel1** » 24 Jul 2012, 10:35

Re: Quick cycling with very cold air.
I had this exact problem a few years ago with my 97' 850 (100K miles) My local mechanic friend was baffled at first and then he reported that I had a dirty sensor. He told me he cleaned it off and reset it. Afterwards it ran fine. (4 yrs) until recently when I seem to have developed a tiny leak in my evaporator... So check the sensor for sudden quick cycling with cold air on and off. Sidenote: Be careful of overfilling these older systems as they are known to leak in the hard to reach seals at the evaporator coil. Good luck and as always take your time and be careful.

KlubMarcus · Post by **KlubMarcus** » 24 Jul 2012, 16:00

dbeckwith wrote: I know my step-daughter did nothingto it in the past 2 years. That is the main reason I confiscated it from her. One time she ran it without water, another she came home with smoke pouring out from hood, and another time she didn't even make it home and then I am left to pick up the pieces

I've successfully troubleshot your problem. Trade in your daughter. Obviously the root cause of your car troubles.