A/C question 1985 S10

Is it normal for the S10's A/C compressor to cycle off and on about 6 times a minute at moderate speeds?

Reply to
techie
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only if its blowing 38 degree air I bet it isn't,so that indicates a leak and you are low on freon. Now is it a very slow leak or a recent leak? Converting to R-134a at an AC shop would be best. No, that CRAP they sell at walfarts autozombies etc is CRAP, those DIY kits are a JOKE.

Reply to
Im Right

Im Right" said on Thu, 26 Jun 2003

13:13:08 GMT:

In that case, it's normal. :)

Actually it's currently right at 40 degrees at highway speeds on an 80-degree day. I've tried cranking the pressure sensor up and down. At a few pounds higher PSI the cycling gets quite rapid (about a 3-second cycle), at a few pounds lower PSI (where it is now) it cycles about once every 10 seconds at cruising RPM's or not at all at lower RPM's. I may try cranking the sensor down even more to see if that will completely stop the cycling without freezing the system up - but first I wanted to make sure I wasn't trying to fix something that ain't broke.

The high-side pressure is a touch higher than I'd like and from the way it cycles I'd say that the low-side pressure wants to be just a wee bit lower than it should be. Not enough that I'd worry if the system were working right, but if there's a problem then the slightly-off pressures might be telling me that a screen or orifice is partially blocked. However I'm not going to open the system up again unless the problem gets worse. The compressor cycling is a little annoying but it isn't going to hurt anything, and I can easily live with 40-degree air.

Neither. After assembly I vacuum-tested it. Then, just to be sure, I added a UV dye when I pressurized it.

True enough for the average consumer but any halfway competent driveway mechanic should be able to do a R134A conversion themselves. Problems are rare if you do the job right - in other words, if you flush all the old oil out of the system, replace all non-R134A components with quality parts, draw a vacuum, and test and refill by-the-book.

They're worse than a joke, they're a fraud that's not only cheated millions of consumers but in many cases ruined their expensive A/C components. I don't know how the manufacturers get away with it.

Reply to
techie

Elbert Clarke said on Thu, 26 Jun

2003 03:10:24 GMT:

I was afraid of that...

I just finished a R134A conversion, and did it by the book (replaced hoses, evaporator, compressor, etc, drew a vacuum, monitored low and high-side pressures as I added R134A, and so on). More likely it's a clogged orifice or somesuch. I just wanted to be sure before I went looking for a problem that may not exist - on some vehicles, it's normal for a compressor to cycle off and on at about that rate to keep the evaporator from freezing up.

Reply to
techie

How do you draw a vacuum at home? My last conversion, my mechanic let me use his A/C vacuum machine, but that's 20 miles away, and I have another car I want to convert.

Jeff

Reply to
jeffNOSPAMgodfrey

Go buy a cheap vacuum pump OR hook the line up to your intake manifold with a brake bleeder kit. Or the other option is to use a mityvac unit but it involves a lot of squeezing the handle.

Reply to
Steve W.

Drive the 20 miles and use your mechanic's vac machine. Even if you have to pay him. That would be a lot cheaper than buying a pump that is adequate for the job, and using engine vacuum or a little Mity Vac is laughable.

Dave

Reply to
Dave Brower

Yep. I used to have a neighbor that made one. Took a LONG time to evac a system, but it worked.

I've used these in the past. It blows air over a small orifice creating a vacuum behind the orifice. They work well but you'll need a VERY large compressor to keep up.

Dave

Reply to
Dave Brower

You have a 200hp air pump nestled in your engine bay. Talk to your "mechanical type" buddies and be creative. I bet you can come up with an idea that works. Good Luck, JR

Reply to
JR

Ok. I'll take that bet. The average automotive engine in good condition will draw approximately 18hg of vacuum. That's a far cry from the minimum 27hg(29 is better) required for a/c evacuation. You can just put my winnings in my Paypal account. ;-)

Dave

Reply to
Dave Brower

You're right Dave, I spoke too soon. Everything I read says 14-22 inches Hg. My bad, where do you want your cookie sent? (bg) JR

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Reply to
JR

well I can tell you that fast cycling of the compressor is a classic sign of low freon. Thats not to say that maybe one of the switches incolved in the systtem may be faulty.

Any time you replace the compressor or any majore comp>Elbert Clarke said on Thu, 26 Jun

Reply to
Elbert Clarke

I wish I'd read this before I converted mine. I didn't see where the consumer conversion kit said anything about flushing out a system to get the old oil out but followed the directions and I haven't had any problem with mine for well over a month now. Its not as cold as I'd like, but its not bad. If it has any leaks they must be very slow leaks because I'm not able to add any additional r134a since I first filled it up. The system was darned near empty, almost no pressure, before I started and I have no way of knowing how long it had been that way. The power plug to the compressor was disconnected and fried like someone had taken it off when the engine was hot and left it on the intake manifold. Chevy dealer told me the compressor was out because he couldn't spin the clutch on it by hand. All it needed was to be plugged in. Is it any wonder why people don't like dealers? My walmart conversion kit has worked fine so far.

Hatt

Reply to
DJ Hatt

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