Air Compressor Newbie

[mutfunds]

New to the boards and need some experienced help. Tried my A/C yesterday and it didnt work. brought it to my mechanic where he bleeded the system and replace it with new freon in hopes that the compressor would kick on. it didnt. removed the battery and re loaded freon, didnt work. Didnt have my owners manual and we couldnt find a fuse. could it be a fuse? The damn compressor wont kick on. He said I may need a new compressor and the part alone is $1000 bucks!!!!!! shes an 03 with 110k on her. any suggestions would be greatly appreciated!!!

[dannoaz]

There are a number of things that may stop the compressor from kicking on. I don't know specifically about the CTS, but I am familiar with other GM vehicles. Normally, there is a pressure switch on the system. A certain freon pressure trips this switch, which allows power to the compressor. If the freon is low on pressure, the switch will break the circuit of power to the compressor. It sounds like he filled the system with freon. That should satisfy the switch limit. But, the switch could be bad. Or the power getting to the switch could be bad. Or the control unit may not be working. Or..Or...Or....

I would check for power at the compressor wires with everything on. If it is not getting power, then you need to trace it backwards to find the problem. If it is getting power, then everything is working except the compressor itself. In this case, then the compressor clutch is shot. In some cases, you can replace just the clutch and not the whole compressor. Maybe not on this vehicle?

So the power normally goes like this:
Control (in passenger compartment) --> Pressure switch --> Compressor

On other systems (again...haven't studied this one yet) you can jump the switch temporarily. You must be shure that you have a good amount of freon before doing this. That is the function of the switch anyways. Low freon and jumping this switch would be real hard or damaging to the compressor.

If you have to get a new compressor you can save a lot by changing the compressor by yourself. Just buy a compressor online. It looks like the compressor is $859.35 list, but you can get it for around $450.00. I have changed it myself and gone to somebody just to fill. They normally charge around $60-$100 to fill. Maybe you could find a mechanic that would be willing to install the part that you supply? I have always done this myself and don't have experience with the mechanics.

What city are you in? Maybe you could get by without AC? Here in Arizona it is almost manditory.

Dan

[mutfunds]

Dan thanks, I cant get by without air in pittsburgh. The summers can be brutal. Unfortunately I cannot even change the oil on any car without making a mistake, but i will bring your post to my mechanic since he really didnt know how to trouble shoot the problem. By the way, is there any fuse that could be blown that would effect the compressor from starting?

[dannoaz]

Look in your owner's manual. Under "Service and Appearance Care", subcategory "Electrical Systems" the 2004 has relay and fuse information. The Underhood Fuse Block has the following that seem to be related to AC:

Relay - CMP CLU RELAY MICRO - Compressor Clutch
Fuse - COMP CLUTCH - Compressor Clutch
Fuse - CCP - Climate Control

I am not sure of the exact flow, but each seems to be important to AC. I would have to study the Helm manual to fully understand. If I'm going that far, I would have to send you a bill. LOL

Assuming the 2003 is the same as my 2004: I would swap the Compressor Clutch Relay with the Fog Lamp Relay, which is right next to it. On mine, they are the same relay number. You can leave the "non-essential" item, Fog in this case, out for this test. As the manual points out, you can normally tell if the fuses are good just by pulling them and looking at the strip of metal inside. If in doubt, swap them with another non-essential fuse or a spare. Make sure to swap anything with the same type. Don't put a 30 amp fuse where a 20 amp belongs, as it is unsafe for the system.

If you end up thinking it is electrical, try to find an automotive electrical specialist in your area. These shops specialize in electrical only. In our yellow pages they are in their own section called "Auto Electric Service". I used to maintain a small fleet of vehicles. When I couldn't figure out an electrical problem myself, I took it to them. The shop that I went to was amazing and didn't gouge on prices. I've heard stories of similar great experiences at other shops.

Pittsburgh, huh. My first reaction is "that's not hot, you should try 120 degrees". But, I'm sure it is plenty uncomfortable, and more humid than our baking, dry heat. Try checking this out yourself. You will probably get to know your car better along the way. If things get too hard, deep breath, one or more ICs, and try again.
Dan