fixing a/c on a 1997 cavalier
 

I know this won't help my FE but it is something I have been meaning to do for a while. I didn't have the money to take it to a shop (actually, didn't care that much)

my system is completely empty. I had a lose nut that was letting all of the r-134 out of the system. when I say lose, I could spin it with my finger. that has been fixed but the compressor won't come on to accept more. the wal-mart a/c fix it kit doesn't do the job.

here is my question. I have heard that there is a pressure switch on the high pressure side that has to be closed in order to get the compressor to come on. in most applications you can short this out with a paper clip or something (at least that is what I have been told) after removing my harness from my switch, I have 3 wires (not two).

am I looking at the wrong switch? if anyone knows where to get wiring diagrams for free, I am game for that too. all the ones I found have to be paid for.

any help would be appreciated.


Side note: this will actually help my overall "FAMILY" mpg as we take the element a lot of times because of the a/c issue. the element has gotten as good as 26 mpg but that still is nowhere near what the cav is getting me.

thanks

Would running it dry cause it to overheat or fail?

the oil in the coolant lubricates the system.

the pressure valve keeps it from burning up if you do have a leak and you don't know it.

I just need to run it dry for a short period to get the stuff to the high pressure side. I can't put it directly into the high pressure side. the compressor has to pump it there.

Some AC systems do have a fill port on the high pressure side- you should never use it with the compressor running- but if you have one, using it might solve your problem.

I have read that anytime the system goes completely empty, water vapor gets in and can really mess up the operation of the AC system. In your situation, you likely need to replace the receiver/drier. It will remove moisture that got in to the system.

The alternative is to have a shop replace the freon or at least vacuum pump your system and then give it back to you for you to replace teh freon. They will apply an extremely high vacuum to the system- this will remove the water (it will "boil" under that strong of a vacuum) and if it holds the vacuum they will know that there are no other leaks.

my problem with that is the cost factor.

what does that usually run? I don't have much money for this project thus the reason I am doing it myself. I wonder what a shop would charge for it. the a/c hasn't worked right in about 4 1/2 years.

I may just call it a wash and keep an eye out for a car with working a/c that is cheap (a replacement that is)

It looks like $35 for the drier at Autozone. Probably about $40 for the freon refill kit.

Yeah, definately if you can't won't vacuum the system dry, put a new drier on it. If you have a friend/neighbor that works in a/c repairs they may have a vacuum pump they can loan you for a day. I know several people I can borrow one from whenever I need to use one.

-Jay

I assume that the dryer install is pretty straight foreward?

I can stand to spend $35 and I have the refill kit at the house. that was a failed attempt about a year ago. I even got the one with the gauge. fancy stuff.

Yeah, usually its integrated into one of the refrigerant lines, Just replace the line, and its done...

quick update:

my system was not empty.
the compressor does come on.
it was low so I filled it.
still no cool air.

it only took a little to fill it back up. I decided to empty the low pressure side. I pressed the valve in with a screw driver and went until there was no pressure. I then filled it until it was full (engine off).

when I filled it the first time, I filled it with the engine running and the needle vibrated but still in the full position. after I cut the engine off, the needle was in the yellow alert area so I emptied it slightly.

the end product is still that my air doesn't work. anyone with more ideas, I am all ears.

here are some pics of what I was talking about.
https://i40.tinypic.com/33kuark.jpg
https://i41.tinypic.com/24oaceg.jpg