Air Conditioning not working....

[K8JWT]

I have a 1994 Pontiac GrandPrix 4door, 3.1L V-6 engine, automatic tranny.

 

When I turn on the AC all I get is hot air.

 

With the engine running I can see the pulley side of the compressor spinning but the compressor clutch never seems to kick in.

 

Checking the AC fuses and all appear good, checked the AC relay and it appears good but I haven't had a chance to power it to see if it clicks.

 

However when checking the relay port with a multimeter I am finding no power at the control pins of the relay port, meaning there isn't any power going to the relay to make it activate. My relay is the 4 pin type.

 

Any advice???

 

Jacob Tennant - K8JWT

[DiscoStudd]

Have you checked to see if you have any refrigerant in the system? The PCM won't allow the compressor to engage if the system's low on refrigerant.

 

To check, remove the air filter box (the whole box, not just the top) and locate the accumulator (the silver "cylinder.") Look for a blue cap on or near the accumulator. Remove the cap and depress the schrader valve for a second or so. If you have a good charge, you'll get a quick little burst of refrigerant escaping, and if you get nothing, then the system needs recharging...

[K8JWT]

Will go out and check that. The person I just bought the car from on Friday 7/15/2005 said he had tried to charge it and it took refrigerant but never could get it to work either.

 

Jacob Tennant - K8JWT

[slick]

Might have either overfilled it or not enough refrigerant.

[K8JWT]

Might have either overfilled it or not enough refrigerant.

slick94prix,

 

How will I be able to tel if it is overfilled? Underfilled seems evident if nothing comes out...

[slick]

If it is overfilled, it will be too much pressure, and it will not kick on as well.

 

Go to the local auto parts store, and grab some refrigerant, and get the filler that has the built in guage in it. That guage seems to be fairly accurate as to how much pressure there needs to be in the system.

[Whiskey River]

If it is overfilled, it will be too much pressure, and it will not kick on as well.

 

Go to the local auto parts store, and grab some refrigerant, and get the filler that has the built in guage in it. That guage seems to be fairly accurate as to how much pressure there needs to be in the system.

 

But that gauge is only accurate when the system is functioning. The green, yellow, and red zones pertain to the pressure of a running system. If you hookup the can and the gauge reads zero, squeeze the can into it. It may take 2 or 3 cans to fully recharge the system. To truely find out what the problem is, get or borrow a real set of manifold gauges.

[K8JWT]

If it is overfilled, it will be too much pressure, and it will not kick on as well.

 

Go to the local auto parts store, and grab some refrigerant, and get the filler that has the built in guage in it. That guage seems to be fairly accurate as to how much pressure there needs to be in the system.

 

But that gauge is only accurate when the system is functioning. The green, yellow, and red zones pertain to the pressure of a running system. If you hookup the can and the gauge reads zero, squeeze the can into it. It may take 2 or 3 cans to fully recharge the system. To truely find out what the problem is, get or borrow a real set of manifold gauges.

Manifold guages? Please explain???? or do you mean those set of guages on the same store rack with all of the other AC stuff at my local parts store (Advance Auto Parts)

[K8JWT]

If it is overfilled, it will be too much pressure, and it will not kick on as well.

 

Go to the local auto parts store, and grab some refrigerant, and get the filler that has the built in guage in it. That guage seems to be fairly accurate as to how much pressure there needs to be in the system.

 

But that gauge is only accurate when the system is functioning. The green, yellow, and red zones pertain to the pressure of a running system. If you hookup the can and the gauge reads zero, squeeze the can into it. It may take 2 or 3 cans to fully recharge the system. To truely find out what the problem is, get or borrow a real set of manifold gauges.

Manifold guages? Please explain???? or do you mean those set of guages on the same store rack with all of the other AC stuff at my local parts store (Advance Auto Parts)

OK I found them on Advance's web site but they are $75.00 which is a little hard for me to pay right now but as you were saying, the on-can guages are only accurate for a functioning system not the way mine is now

 

OR, Would the best thing for me to do is to totaly bleed the system and refill it from empty?

[THe_DeTAiL3R]

The best thing to do would be to have a professional service it. A/C systems are more complicated than you might think. Sure you might be able to get it working for a while if you put a couple cans in, but if there are other problems a proper flush etc. will keep it working properly for a long time. Moisture, etc, that may get into your system is bad for the compressor and other components.

[Dannymik]

If you refill it to its proper level and you still don't hear the compressor clicking on then its probably your clutch thats shot. If thats the case then you either have a garage do it or purchase a compressor yourself and give it a shot. I had this happen on my '95 Cutlass and chose not to fix it and sweated it out. As C-bad stated, A/C units are a little tricky to work on.

[Whiskey River]

Here is what you can do. Get a can with a gauge on it. Hook it up and see if it is registering any pressure. If it registers pressure, then the likelyhood of moisture getting in there is small, if it reads 0 pressure, take to to an AC specialist. If the gauge is reading pressure, take out the compressor relay, and jumper the compressor to force it to come on. The pressure should drop below 30 psi rather quickly. Follow the gauges from there on out. One thing to keep in mind is that these cars use a V5 compressor. It is a variable displacement compressor so you can overcharge it an not see the effects on a single charge gauge. Manifold gauges are far better suited for this task but I understand the price concerns.