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A/C question


jsgold
07-27-2005, 09:34 AM
I have worked on about everything on our 91 Corsica since we bought it (new) many years ago, however I have not dealt with the air conditioner. when it was newer I had it charged a time or two but did not attempt it myself. It has a very slow leak9 no one could find) that required a refill every 1-2 years and we stopped fooling with it about 5 years ago since it was only used seldom. Now my son is using it and it needs converted to 134 and reharged. I hear conflicting information on replacing hoses etc. to run 134, some say yes, some say no, just use existing stuff. I see these kits that let you covert over for around 40 bucks. My questions are - will this suffice or do you HAVE to replace other items, and 2- the only car I ever recharged was an old Dodge, and, to get it to fill you had to "force" the compresor to run by using a wire, otherwise it would not work. Do you need to do this on GM Corsicas, or do you simply feed in oil / R134 until it kicks on? I know the compressor is still good, but won;t engage because too low on R12. (I just replaced the radiator in this car if that makes any differance). There was a little pressure still there, but very small. I was careful to keep everything clean. The car will only be driven for another year or two, so I don't want to pour a lot of money into it, just want to keep my son cool for a while since it is so darned hot here.

ctesla
07-31-2005, 09:53 AM
on your Corsica; shouldn't need anything but the higher priced conversion kit. no hoses, compressor, etc. but it is critical that all the R12 is out of the system prior to the 134 charge.
WVa is hot but humid as well? with the age and mileage, you might spend an extra $60-80 and have the reciever/dryer assembly changed while the system is empty. you do not have to do this, but while the system is empty, it is the perfect time, and a new dryer will insure more years of operation, plus if this just happened to be the slow leak item: BONUS! no recharging every year.

most parts houses will have or order the dryer unit, and stock the A/C kit (some of the kits have CD-ROM/DVD on 'how-to' step-by-step)

hope this helps,
ctesla
ASE cert.instructor

ctesla
07-31-2005, 09:55 AM
...also, shouldn't have to "force" Corsica's compressor; as the GM system fills (make sure A/C and fan on dash set to high), compressor should kick on its own, filling and charging system.

jsgold
07-31-2005, 10:22 AM
Thanks! That helps a lot!

CDJr
07-31-2005, 12:28 PM
Actually, while you have it empty, it would be a good time to try to find the leak first. 90% of the time, it will be easily fixed by replacing a few O-rings on the hose connections, especially on the high-pressure side, since this is where theyre prone to leak. Look for oily areas around the fittings, thats an easy way to spot them. As far as changing it over, if you can lay your hands on a lil R12, itd be better to recharge it with that, especially if you can fix the leak. It cools much better, plus itd save you the cost (and trouble) of converting it over. I saved 2 cases of R12 to use on my Firebird Im building and a few friends cars that use it. Not to mention that 134a is outrageously priced these days, its almost as high as R12 lol. And the reason you bypass the low-pressure switch to charge it is mostly to save time, as it takes awhile to charge it when the compressor only runs for 3-4 secs at a time, it wont hurt to jump it out with a piece of wire, just make sure you remove it when youre through and dont let the compressor run while the system is empty. Hope this helps.

gmcorsica93
07-31-2005, 02:40 PM
Don't waste time!!!..after you change to R-134a,the A/C not cold like using R12. I ask GM to do the job on my Corsica back in 1998..cost nearly US$500 !!!!Now I spent more money on the A/C than anywhere of the car !!!

jsgold
08-02-2005, 07:59 PM
Thanks for all of the advice! We have put the A/C on hold a bit. The system still had a little pressure left even though it had not been run in a long time. Might try the conversion kit Advance has and see if it will work for a year or so, even at average performance. If I find the leak and easy to fix maybe we will look at further repairs. I would go ahead and replace everything if the car did not have 176K on it.... Still, the parts seem to be pretty cheap, especially on Ebay. We gave the car to my son for a first car and is up to him on what we do. He might just keep driving as is. One thing though. If shorting the compressor makes for a faster charge, where do you short it? I don't see any information anywhere so far how to do it.

CDJr
08-02-2005, 10:26 PM
There is a wire that plugs into a switch on the low-pressure side, probably very near the drier, and it keeps the compressor from running once the pressure drops below a safe level, to keep from burning up the compressor when its low on refrigerant. You can unplug it, jump it out, and force the compressor to run. ONLY do it when you are charging it, or youll wind up burning up the compressor. But like I said earlier, I would find and fix the leak first, expecially since itll probably only take a few O-rings, cuz once you charge it up, its too late until it leaks out again, or until you remove all the refrigerant.

jsgold
08-02-2005, 10:36 PM
May be hard to find any leak since there is no longer any pressure in system. I noticed Advance has a kit that has new O rings as part of retro kit, might be worth a try. I have a leak detector I bought recently so I can use that to d/c later, just in case. Will post if we results later if we go ahead.

jsgold
08-19-2005, 07:37 PM
I can't seem to find any kind of inlet for the freon. I see where it supposed to be underneath somewhere, but where? I see the high pressure one at the top of radiator area. Even my GM manual does not show it, only mentions it. Not the best service manual. this is a 91 , 3.1 v6. I am going to raise the front end up Sunday as high as possible, maybe I can see it better then, but if anyone knows where this thing is, let me know.

jsgold
08-20-2005, 07:34 PM
I can't seem to find any kind of inlet for the freon. I see where it supposed to be underneath somewhere, but where? I see the high pressure one at the top of radiator area. Even my GM manual does not show it, only mentions it. Not the best service manual. this is a 91 , 3.1 v6. I am going to raise the front end up Sunday as high as possible, maybe I can see it better then, but if anyone knows where this thing is, let me know.

I guess I found it, on the dryer. Once I raised it up it was easier to find..
and of course once under there I found several bare wires around the starter that now must be repaired. Funny how you try to repair one blasted thing and run into other crap to fix. Guess the heat over the years has made the wire brittle. Normally I would not gripe about wiring, but not a lot of room to work with...

jsgold
08-23-2005, 10:52 AM
Well, the conversion went better than I expected. Unsure how long it will hold given the age of the car, but, working very well if not better than original. made a jumper wire set, converted the inlets to R134 type and recharged. I used a conversion sold by Advance that had3 cans of oil / r134 / sealant for small leaks. It came with a CD-ROM that walked you through it and has a pressure guage on it as well. I should have flushed the system out, since i had taken the system partly down when replacing the radiator. But I think it will be OK. Will watch for pressure loss and if it holds up OK for a year or two i will be pleased.

steelerguy
09-27-2005, 06:03 PM
Well, the conversion went better than I expected. Unsure how long it will hold given the age of the car, but, working very well if not better than original. made a jumper wire set, converted the inlets to R134 type and recharged. I used a conversion sold by Advance that had3 cans of oil / r134 / sealant for small leaks. It came with a CD-ROM that walked you through it and has a pressure guage on it as well. I should have flushed the system out, since i had taken the system partly down when replacing the radiator. But I think it will be OK. Will watch for pressure loss and if it holds up OK for a year or two i will be pleased.

Did you evacuate the old oil in the system before adding the R134? Autozone says to do that and replace it with PAG oil. You definitely cannot add the new PAG oil to the oil in with the old or it turns to gum.

I have to convert my system this weekend & would love to put it off a month if I could just remove the R12 and charge the existing parts with R134 and the existing oil. Have the same conversion kit you have with 3 cans of oil. Have a slow leak at the compressor manifold hose & from the compressor.

If it runs for even a month, I might just chance it. Will change the compressor, accummulator & the little screen in the line when I have more time.

To be clear, is it still working & how long has it been working?

jsgold
09-27-2005, 06:47 PM
So far, OK, except that the old leak bled off enough pressure so that the compressor stopped until I topped it off with a very small amount of R134. I have read where the system should be changed as far as oil is concerned, but the maker of the kit says no. If it were a newer vehicle perhaps I would have, but am not at this time. If my son keeps the car until next spring I plan to find the leak and repair it, if possible. If I get done with my current problem (my old Blazer) I may go ahead and trace it before it gets cold. One thing I see is that Corsica stuff is pretty cheap when bought on Ebay, so if I wind up replacing some stuff, OK. Heck, the entire system can be replaced on ours pretty cheap if need be. If it is only O rings then great. Ran one month to the day until I had to add additional R-134.

dallaslouie
09-28-2005, 04:53 PM
my 94 corsica ac blows the thru the defroster vent and floor. I changed the ac/heater switches and still blows the ac the same way does anybody have a answer to the problem.

steelerguy
09-28-2005, 05:55 PM
my 94 corsica ac blows the thru the defroster vent and floor. I changed the ac/heater switches and still blows the ac the same way does anybody have a answer to the problem.

Don't know anything about corsicas but I do believe that vent routing & rerouting is done by vacuum lines & a vent control module. Check a manual or look under the dash for a vacuum module. The line to it may be disconnected, broken or cracked. You might even be able to hear the vacuum leak while changing the defrost/vent positions. Never actually fixed a vacuum problem myself, but have watched the A/C flow go to the defroster vent when removing the vacuum line on the vent control module on my Durango. It is on the passenger side, just under the dash.

Good Luck

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