AC cycling constantly

Either bad pressure switch or still low on Freon. I'd guess the latter.

If you had to add freon you have a leak some place , but you may have some left from the refill you had but I would say it will not last long . Take it back to the place you had the test done to get it repaired correctly . I had a Ford dealer do the same test and refill done as you did and a few days later it was back to no cool air again . When I returned the car again they did find a leak and repaired it . They give me a bill for the repair + a freon refill I said no way would I pay for the freon again as it was there problem they did not find the leak . After talking with the MGR they dropped the charge for the freon . Good luck and please let us know how you make out . Fox .

fly > Hi, guys.

Thanks to those who responded. My mechanic said freon will eventually bleed out through the hoses like helium through a balloon, but slower. Never heard that one before, but maybe?? The constant recycling was apparent right away after I picked up the van from repair. It's been a couple weeks now, so I don't know. One thing I noticed is that it doesn't cycle while I'm idling. But the minute I start moving, we're off to the races.

a good ,properly working system will cycle often. both my 99 crown vic and

Sounds like BS to me. I've had many vehicles that were still running on the original freon charge after 15 years.

Sean

Depends on the heat load and compressor speed. At 68* ambient, yes, the AC will cycle more frequently. At 95* ambient, the compressor should stay engaged longer.

Most cycling clutch systems are controlled by a pressure switch (or temperature sense) on the low (suction) side of the system, pressure does not -build- on the low side.

On Sun, 07 Sep 2003 02:22:58 -0400, Sean Conolly rearranged some electrons to form:

Actually, it's true, molecules will slowly penetrate the hose material. But the amount is so small, it is negligable. You're more likely to get leaks in the compressor seal, or the joints/o-rings in the hoses.

I am no A/C expert but, if the pressures are good at high idle with no short cycling and, the short cycling is occuring only at idle, I would suspect a bad IAC that cannot maintain sufficient engine idle speed. Had this problem earlier with my CV. The system has a relay that drops the A/C clutch when the idle speed drops too much to sustain proper alternator voltage output. As soon as the compressor is dumped, the idle speed rises just enough to "see" proper voltage to engage the clutch. AS soon as the pressure begins to rise again, the idle again drops repeating the process resulting in compressor cycling that you notice. BTW, the orifice tube A/C is controlled by cutting out the compressor on the pressure drop cycle and back in on the pressure rise cycle. There is a high pressure cutout switch but, it is not likely that you have that much excess pressure unless your A/C guy is really off the mark. If the cycling is proper when your manually hold it at high idle, that rules out the clutch cycling switch.

This (above) is not correct and you should ignore it. As another poster stated, the system will tend to cycle quickly in colder weather. This is because more of the Freon is existing as a liquid in the condenser, so the pressure gets lower everywhere. If it's 100 degrees outside it may stay on all the time. Fords cycle more quickly than I'm comfortable with, so your system might be fine.

Also, the mechanic's comment that Freon will "ooze" out of the hoses is just irrelevant hand waving. It's not exactly a lie, but it has nothing to do with the problem. If it made sense to you maybe you should restate your problem.

I'd venture that it is low on refrigerant

it doesn't do it at a stop because the lack of airflow thru the condenser results in higher overall system pressures; when you start moving, the condenser becomes more efficient and low-side pressure drops, and it cycles more frequently

my 88 Ranger, converted to R-134a cycles at about 6-8 seconds, FWIW

That doesn't sound efficient at all. :/ I don't want mine to cycle that often, and it didn't back when it was working either. ;)

Don't forget to get back here on a.t.f and let us know what it really is ok?

Alvin in AZ

tell us what WHAT 'really is' ?????

Refridgerant doesn't just disappear, it leaks from someplace. A pressure test isn't the best way to find a refridgerant leak in an auto AC system. Introducing a dye into the the system and then checking every fitting with a black-light is a better way. There is also a 'sniffer'-type electronic device, but I've not used any of these.

Me too! That would drive me to distraction. There are a number of possibilities: undercharge/overcharge, bad low-pressure switch, clogged orifice tube, low on oil charge, too much moisture in the system. Possibly even a compressor malfunction and/or clutch problem(slipping).

A compressor that cycles very rapidly is usually a sign that the system is low on refridgerant. A quick test: bypass the low-pressure switch with a jumper wire. The compressor should run continuously. Feel the inlet/outlet tubes of the evaporator>if they feel the same temp, replace the switch and retest.

The original diagnosis should have been done with a manifold gauge installed in the system. A good AC-system mechanic can decipher the readings during various testing conditions imposed on the system and pin-point the problem.

I rebuilt my 23yr old F100 R12 AC system about 12yrs ago. It cycles as it always did, about once every 2-3min, once every thing is 'normalized'.

I also rebuilt my '87 Cad system in '98 and converted it to 134a. It cycles about once every 3-4min.

Yes, hoses will leak, but it's at the atomic level. It will take one hellofa long time to leak even a small portion of refridgerant.

Hope some of this helps.....

Dave S(Texas)

...-it- what it (the trouble) really turns out to be...

What do you expect from a guy that was born in AZ? Been heat stroked a couple times (K+ hurts) and lightning struck (woke up laying on my back, arms and legs in the air, like a dead cockroach)

What deck? You thought I was just missing a few cards huh? Fooled you. ;)

Alvin (borrun in AZ)