First of all, I would like to thank the folks who have helped me in the past with always great advice and also thanks to those who have posted techniques and instructions with photographs, they are priceless.

Okay, maybe my AC has not gone wild, but has definatley a mind of its own... I have recently revived my good ole' '96 850, replaced PCV, Timing belt and idler, water pump, tensioner, Alternator and a few other goodies and after feeling good about the critical stuff, I am looking into a problem that I have had with the little car since before I parked it.

The AC works well when I first start the car and as long as I dont move the car and is idle, it works great! As soon as decide to drive somewhere, the whole thing just says "i dont wanna work" and wont come back on until maybe... well, that's just it, unpredictable. If the car cools down and restart in driveway, maybe it will work again until I go somewhere.

I am not too sure what to look for and where to start, so I ask if anyone has any good suggestions or if they have encountered a similar problem.

Thanks before hand for any help!

 

Could be any number of things. Do you understand how an AC system works?

If so, you can do some trouble-shooting and figure out what the problem is (and I/we can try to help with that) but if not, suggest you take it to a reputable auto AC shop.

 

Try shimming the compressor clutch. There is a DIY on how to do it here on the forums, you may have to search for it, but it worked for us when we were having the same problem. Also check your freon level.

 

Because you say it works ok when started and left at idle I'd say it's the clutch on the end of the compressor as Psaboic suggested. The clutch wears with age the same as a clutch for a transmission. As the AC cycles on and off over the years some metal gets worn off and the gap between the plate that drives the compressor and the plate that's driven by the belt widens until the electromagnet that pulls them together can't pull them together enough to prevent slipping or can't pull them together because they are just too far apart.
It's not specific but usually they figure the gap should be about the width of a dime. If you can get one down there in that gap and it's loose it's likely the clutch lets go once you try to rev it up as the resistance at idle to keep those two parts together and spinning is less than what's needed once you try to accelerate and you're trying to pressurize and pump more volume through the system. That's when it gives up and slips, no ac.
Just my guess but it fits with your symptoms.

 

I must say i am slightly disappointed... I came in here looking of a set of boobies...

With that said

It could be clutch re-shimming, a clogged orifice tube, bad high pressure switch, or just low on freon.

First thing i would do is take it to get the levels read, most places will do this for free as long as they dont add freon.

if its low, Which i believe it is, i suggest having the system vacuumed before it gets recharged..

once thats done go from there

 

Usually with low freon you'll hear the clutch cycling often and it wouldn't make a difference idling or cruising.

 

Depending on how low it is, when you accelerate it will shut off, crusing at anything over 2k will keep it off

 

When mine was low on gas it would shut off over about 1800rpm, the air con guy I went to said when you up the revs it forces all the gas over to one side, effectively shutting off the low pressure switch, after about 10 minutes it would even back out and turn on again for a short while.

 

Hi Everyone,

Thanks for the input and sorry for the lack of boobies, Matty, lol!

I did read on the forum somewhere, I believe it was a sticky, about a "broom stick" test. I tried that and that worked... didnt fix anything, but confirmed what most have suggested about shimming the compressor. I have to say that a long tima ago when I first encountered this problem, it occurred to me to by pass the electrical wire and "jump it" straight to the + battery terminal. I did this "to see if it would work" and it did! the compressor ran okay. and never clicked off even when driving.

Of course, this was not a solution, just a test which led led me to believe that perhaps a relay may be fudled up or a pressure switch, etc... of course I could not find anything wrong with any of the rest save for the fact that the dainty wire that connects to the compressor perhaps developed some added resistance along the circuit it belongs to and does not deliver enough AMPS regardless of the 12v reading I got from it, hence why it works when I plugged a direct and fatter wire to it directly from the battery.

Anyway, long story short, I never thought about the clutch being the problem, which makes perfect sense to me now that you all have mentioned it. I guess the added AMPS from the thicker wire and shorter run to the compressor kinda compensated for the added gap which under normal circumstances would prevent the clutch from operating as it should.

Next question is, would it be worth my time and effort to temporarily install a relay to the original compressor clutch circuit and run a bypass that goes directly from the Battery to the AC clutch? At least until I have to tear something else apart on that end of the engine that would give me perfect clearance to the AC and fix it properly?

Thanks again all for all the great input!

Art

 

I believe there should be something here for everyone !!!

Boobies and beer, what more could you want ??

 

Well, I finally got around to doing the re-shim as suggested by most of you guys and it worked, my 850's AC works well now.

Thanks for all the help and a shout out to Tech who posted the "how to" with images, it was very valuable.

Art

 

Glad it was something relatively easy for you, and glad we could help!