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93 Geo Prizm A/C Questions

esher127 on Mon June 21, 2010 8:11 PM User is offline

Year: 1993
Make: Geo
Model: Prizm
Refrigerant Type: R12

Hello all! I have a 1993 Geo Prizm LSi that I purchased a few months ago. When I bought the car the A/C didn't work, but it was so cheap I thought that I wouldn't mind. Well, it's been so hot that I've started to mind! So the last couple of days I've been trying to figure out what's wrong with it and I'm at a total loss. If anyone could give me any pointers I'd really appreciate it! Here's what it's doing:

- When I push the A/C button on the dash, the engine revs go up but I never hear the compressor click on
- The air temp coming out of the vents doesn't change whether the button is pushed or not
- I've checked all of the fuses, and they're all fine
- The black box things, (relays?) that are in the fuse box for the A/C I'm not sure how to check... but they're present!
- The belt doesn't squeal or anything, and the compressor pulley seems to spin okay

In my desperation to get this working I bought some stuff called Freeze12 and a R12 hose... but didn't get very far with it. I've re-filled my leaky Jeep's A/C with R134a a bunch of times, but I can't figure out how to do it on the Geo. The only ports I can find are on top of the compressor itself and one is labled "S" and the other "D". I've NO idea which one, if either, is the low pressure port. So for fear of the can exploding in my hand I've done nothing with it. I can tell you that in my poking and prodding if I push the needle down on one of those ports gas shoots out... so I think it has coolant. I don't have any R12 guages to know how much.

So... that's all I have. Any ideas? Anything? I don't have the money to take it to a mechanic and I don't want to spend a fortune on it. I only paid $900 for the car and it just doesn't make a lot of sense to dump hundreds into the A/C system, so I'm hoping it's something simple/easy/that I can do myself.

Thank you all!!

chris142 on Mon June 21, 2010 10:06 PM User is offline

The S stands for Suction which is your low pressure side and the D stands for Discharge which is your high pressure side. We do not like the Freeze12 stuff here. It's mostly R134a so your better off retrofitting the car over to R134a.

rastoma on Tue June 22, 2010 5:31 AM User is offline

Does the compressor click and engage when you press the AC button? Just because the pulley spins freely, that's just the pulley. You will see the center of the compressor star spinning and should here a click sound when pressing the a/c button so have someone press it while you watch the compressor.

esher127 on Tue June 22, 2010 8:06 AM User is offline

There's no click... doesn't even seem like it's trying. The engine revs go up when I press the button, but the clutch never engages. That happened on my Jeep once too, and it was just the fact the pressure was so low that it wouldn't allow it. Once I added more coolant, all was well. However I don't think that's the issue with the Geo....

After learning that S means Suction (Thank you, btw) I went back out, hooked the freeze12 can up to the S port, started the car, turned the A/C on, and opened the can. Nothing. After letting it run for 5 minutes or so the can is still pretty much full of coolant. I could hear it moving a bit, but that could have just been inside the hose, I dunno.

mk378 on Tue June 22, 2010 2:25 PM User is offline

Don't mix refrigerants! A mixture of R-12 and the R-134a based Freeze 12 will not perform properly.

Sounds like an electrical problem or the clutch. Controls on all cars are different, but generally if the engine revs up, the system is trying to engage the compressor. Check if power is reaching the compressor clutch wire.

Also don't be tempted to jump the compressor to the battery with the engine on, if the condenser fan isn't on too, you will blow a hose out. This is a good test with the engine off though, to see if the clutch will pull in.

You can check if pressure is present by unplugging the pressure switch and checking it for continuity. If there is continuity, compressor should run. If no continuity you need to use proper tools to service the refrigeration system.

Edited: Tue June 22, 2010 at 2:32 PM by mk378

esher127 on Wed June 23, 2010 8:49 AM User is offline

Given the location of the belt/fans/compressor, there's no way I'd stick my hands in there with the engine running. lol

How do I jump the compressor? Just some jumper cables from the battery? Are there terminals on the compressor?

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