Weird AC problem.

Perhaps the AC-compressor was stuck. Did you feel the enginepower increase and decrease upon switching the AC on and off. There's a thermoswitch that controls the operation depending on the airtemperature. The AC should switch on and off on a regular basis.

Jeroen

If it continues - - There may be moisture in the system. Some of the pressure switches were over and under pressure switches, and these can cause problems when the system is actually a bit overcharged. If the system is undercharged, it may be freezing up, at least until the under hood temps are high enough to help prevent freeze up.

Finally, as old as a 92 is, there can be crud from just wear that prevents a reed valve from closing. If so it may clear itself by getting stuck in the filter dryer.

Hopefully, the problem might just go away, at least for some time, or until the 92 is not used for awhile.

It's always hard to get a handle on such things without being there, and having the gauge readings to go by.

It's never been very noticeable, even when it's working right.

It's been doing this since I bought it 6 years ago.

It's been evacuated and recharged w/o no change.

It's not old, it's young! I'm a 1935 model and some of my stuff still works !

And the gauge readings are always normal but it's always working when it's checked. One thing that seems to always fix the problem is turning off the engine and restarting it such as normal start and stop driving around.

I suppose the best thing would be to call the shop, tell 'em what's happening and tell 'em to expect a call next time it fails, explain I'm on my way there and won't be turning off the key when I arrive.

Then they can say they're too busy to get to it that day.

I'd guess that some self diagnosis is in order. When the problem occurs, and you can pull over. Check to see if the A/C clutch is engaged. You may be able to carefully "thump" it with a piece of wood, or whatever, and see if it engages.

Also, one of the odder problems I've seen had to do with the compressor reed valves. seems that one was broken, worked part of the time, and when it sort of wandered around, did not.

Is the 92 filled with the "old" Freon, or the EPA happy stuff?

Can't even see it!

It's got the old stuff AFAIK.

Wierder and weirder, it seems time and temperature related. Tonight I visited a friend about 8 - 9 miles away. AC worked for about a mile, then quit. I left the house at 6:30 PM with the temperature at

I came home about 10 PM with the temperature about 110F, AC worked maybe 3 miles then quit. I turned it off and back on, no AC but I can feel the compressor kick in. I turned it off again for about a block or so, then back on, it worked great for about a mile then started blowing hot again.

Too damn tired to raise the hood... off to bed.

a friend about 8 - 9 miles away. AC worked for

miles then quit. I turned it off and back on, no AC

block or so, then back on, it worked great for about a

An off the wall guess is that there is a bit of crud floating around, and plugging the orifice. When the compressor shuts off, the internal pressures start to equalize, and may be causing the crud to move out of the way. The next question is when was the dryer changed?

With the old freon, anything you do is gonna be expensive. (Salvage, filter, reuse, etc. requires equipment that was not cheap!)

That's a possibility...

Not since I got the car, probably never.

Fix is easy, evac system, remove receiver/drier and scrap, remove compressor and drain oil, replace with R134a oil, replace compressor, install new receiver/drier, evac and recharge with R134a. Not all that expensive, even if a new/rebuilt compressor is needed, I'v done it with no problems and found the cooling was not reduced at all in spite of reading many comments to the contrary.

Unfortunately, I'm no longer able to do that nor do I wish to pay the cost of having it done. The AC is very likely to remain non-functional.

The reason I asked about the drier is that sometimes old ones become saturated? and little pieces get into an A/C system. The same is true of rubber "O" rings, and metallic particles that get past the filter.

I had one system on a Mazda van that failed (compressor). The amount of crud from the compressor was high, and looked like a gray paste. It was all over. We had to flush out everything. At least the mileage was over

The hardest part is the dis-assembly to get to and R&R the compressor. I really miss the old GM scheme with the compressor on the top front passenger side of the engine.

Not hard at all for me, I just fill the trunk with money and take it to Mike's Place, they R&R the compressor, empty the trunk and it's done!

That doesn't always help, had to R&R the compressor on a Jeep Cherokee, they had a mounting screw that ran through the compressor to the mount. So far, so good. They used a thread that must have been 1,000,000 threads/inch, I cranked on that for 30 minutes to get it 1/4" out! Gave up, dragged the compressor around to the carport and used the air rachet to finish it.

I really miss the old York compressors that were easily rebuilt. Google shows parts are still available!

On Mon, 27 Jun 2011 20:20:00 -0700, XS11E wrote: Could be the expansion valve is going bad. Can seem to be fine in the shop and then do what you stated on the raod. But really need the gauges to see what each side is doing.

Doubt that'll work. If I take in in and they shut it off, it'll work fine when they turn it back on and driving with the gauges hooked up is probably not going to happen.

Last night it died on the freeway and never came back on, when I went home it died again on the freeway and started blowing cold air as I went down the exit ramp. I'm pretty lost as to possible causes...

Was there a bump or two as you exited?

No, I thought of that! It was smooth and I didn't even feel the compressor kick in when it started blowing cold. I'm fairly sure the compressor stays on when it fails but I'm not positive.

BTW, the suggestions of some floating crud blocking an orfice.... woudn't that raise pressure causing the compressor to turn off? I really need to catch it failing to see if the compressor is running but it's too damn hot to get out and look and much too hot to try to raise the hood w/o a pair of oven mitts!

Looks like you need to throw a pair of insulated gloves in the car, and maybe a flashlight. The A/C clutch coil (Now that I think about it) can fail intermittently. I've seen this exactly once in several decades of working on cars.

It's now become very easy to diagnose, it doesn't work at all, ever!

It's going to Mike's Place on Monday, first opening they had.

Since none suggested the cooling fan the $1,000,000.00 prize for the correct guess remains unclaimed!

New fan and a shot of refrigerant and it's blowing freezing cold while running the freeways at x mph (you guys know I'd never speed, right?)

Apparently the dead fan also blocks air flow through the condenser by failing to turn, otherwise it might have worked at freeway speeds???