Air Conditioning Problem

[rs2sensen]

I had my engine replaced about a year and a half ago when I discovered the previous owner had loaded the vehicle with stopleak after cracking the block. (Hey, it held for nearly 30k miles, not bad!)

Prior to replacing the motor, my AC worked fine. Afterwards, it didn't work anymore. I'm guessing that the guys who did the work emptied it and didn't fill it up, or pinched a wire somewhere. I'm hoping for the former.

Anyways... I noticed the AC clutch doesn't kick in at all, so I can't get it to suck in any extra coolant. What is the easiest way to bypass the low pressure switch so that I can fill the system up?

[whiney]

What exactly are you trying to do here? Have you put the system on a vacuum pump? You should almost be able to put enough in without having to start the system up.

[FordMan77]

^This^. You need to evacuate the system and have it hold 30Hg of vacuum for 1 hour. If this holds then the system is good and you can pull in a can of 134A. Once it gets some in there it will take the rest. Keep it on max A/C while refilling and enjoy some cold A/C.

[rs2sensen]

Hey guys,
Resurrecting my old thread...

Finally decided I needed to get my butt in gear and get the AC fixed, as I just moved down to Florida and its HOT.

Anyways, took the car to a shop which did diagnostics on the AC system. They determined that the compressor wasn't kicking on because they felt there was an issue with the ECM. They also leak checked the system, and found no leaks. So...

I had them totally evacuate the system for me. The next day I slapped in a known working ECM, and then recharged the system to the exact weight (very slightly below it, but darn close) specified in my repair manuals while jumpering the compressor relay to get the system to suck in the coolant.

When the system is jumpered, the compressor kicks on with no problem whatsoever and the air is ice cold and perfect. However, without the jumper and the relay installed, the compressor will not come on. I replaced the relay for the hell of it, and that didn't help.

Any ideas of the next steps for diagnosis?

[dsmuts]

if you jumped the relay and it worked it has to be the relay i would think

[rs2sensen]

Thats what I thought too, but I've tried a new relay and that didn't do it. I'm going to test the relays I have with a multimeter tomorrow.

Just to clarify, when I say jumpered, I mean that I used a paperclip to bridge the connections in the socket where the relay goes, not sure if I'm using the correct verbiage there or not.

Thanks!

EDIT: Actually... I just went and tried two more relays. No difference. I also stuck a new fuse in Fuse 28, which is labeled A/C CLU/ABS IGN on the schematic I have. No dice.

Here's the schematic I was looking at:

[dsmuts]

Maybe your controls aren't working right?

[m0ni3l0v3]

I am truly new to this, but i am trying to ask a question and can not figure out how to post in this forum...
but here is my problem...
I recently bought a 2000 grand prix and my ac has not worked since I bought it and I am trying to find out how to go about finding what is wrong with it, with out having to spend a bunch of unnecessary money... any help???

sincerely,
a very HOT driver.

[dsmuts]

If there it's no r134a in the system recharge it with a can with uv dye in it and the dye will show where your leak is

[BillBoost37]

Jumping a relay does not imply it's bad. It typically means the relay is not being actuated normally. Test for power and ground to actuate a relay and you'll know what is missing. From there you can trace things back.

The pcm will not try to turn on the compressor if the system does not have freon.