Pontiac Grand Prix Forums : Grandprix

I'm having trouble with my '04 GT. I have searched here and it sounds like I am low on R134. The ac worked fine last year, but now it does not. I press the button and the clutch does not kick in, but the light lights. I checked the fuse, and its ok. I don't see any obvious leaks and all the hoses seem to be connected tight. I realize that is no guarantee to a leak free system, however, I made one call the other day and the price I was given was over $400 to check and charge. That is probably what I should do, but I just don't have the money to get out the door of the shop right now.

I am hoping that I can get a can or two in the car and hopefully next year I can get it checked out. With the compressor not kicking in, I assume that I have to jump the low pressure switch with everything ready and connected to get the system to receive the gas. When I look at the switch, it looks like it has 4 (edit - 3 actually) contacts. Which are the correct ones to jump?

I'm familar with cars, so working on them is not an issue, however they have all been 1987 or earllier vintage to this point. I really would appreciate a quick pointer or two,

Thanks,

Scott Barrett

I believe there is a a/c clutch relay in the underhood fuse box. I replace a lot of these on Ford products. Yours could be bad, switch it around with another one. Just a thought, Skip

The only way to know is put some pressure gauges on it. Now adays you can buy a can of 134 with the little gauge already on it and add only what you need. It even tells you when it's a good charge. Try it.
Put on LOW SIDE ONLY, it will have a blue cap on it, unsrew the blue cap and you will find a little quick coupler type fitting. You might need to jump the a/c compressor to add it if it is too low of pressure.

Dean

Both of my caps are black. From what other postings here have said, the low pressure fitting is the one by the firewall. That is the one that I need. Is it easier to jump the clutch itself, or to jump the switch (which pin?).

I will check the relay. I never thought of that. That is a great thought. If I can see when I get out of the parking lot tonite (I'm a 2nd shifter) I will check that then.

Thanks again,
Scott

Well, the relay did not work. I am going to call a few more places tomorrow and see if any of the parts stores have a gage for rental or something. Also, I will check other garages for their price too.

you can buy the cans that come with the gauge to refill it

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I have seen them in stores. Is there any issues with the vacuum being diminished? Also, as stated in my 1st message, I would think jumping the switch would be the easiest, but the switch has 3 wires on it. Do you know which to jumper? I don't have the factory manual and I can't find the diagram to show which pin is which.

Well, I did the charge myself, for good or bad. I got a recharge can with the gauge, connected it and pumped the button a few times, then the compressor clicked on. After emptying the can in the system, it only got up to about 35psi. It is a little cooler here in MI today, so maybe that is all it will get. It did feel like cooler air was coming out. We'll see when we get another hot day.

For those that have used the cans of refridgerant, does this sound normal? Should I get a 2nd can? Did I just completely screw up my system?

Thanks,
Scott

i havent used an entire can...sounds like there may be a leak somewhere...

Well you do not really know how much refrigerant is in the system. 35 psi is a little high for the low side. You could have a clog in the system some where that would raise the pressure, but hurt the cooling efficiency. I do not think you screwed up your system. As I said in another thread. the best way to go about a/c work is have a shop with the right equipment check it out. Sometimes you will get lucky and the bottle will work good. If you are going to add anymore yourself try to find some with dye in it, so when you take it to a shop they could find the leak easier.

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here is some tips, felony posted this in another thread. it might not be low on pressure (guage wont tell you volume, just psi...makes sense to me) and this is what he said...

"I'm not sure why but on our cars when the pump is at high displacement it won't cool the drivers side so adding about 12oz more will keep the pump running at low displacement then both sides will stay cool. I had the same problem with my old 97 grand prix. I thought the gates were not opening. I bet I spent three days under my dash chasing vacum lines, and because the gauges told me I had enough pressure I never thought that could be the problem. A friend told me the same thing that i'm telling you. I didn't believe it could be so simple till I added another can of R134A and the pressure stayed the same on the gauges and both sides got colder than they had ever been."

so try filling it with more, if it will take it.