Need a little help with the ac unit in my 2001 chevrolet Monte Carlo 3.4 ltr I just finished adding the 134a refrigerant in the low preasure gauge but by compressor did not turn on the ac relays work but there is no power going to the compressor or pump. Now I took a wire and connected straight from the switch to the battery turned on the compressor but when i remove it, it turns off what other possibilities could be with the compressor what would i start checking

 

Don't know if your car has a temp gauge, but if so, what is temp reading? These engines are designed to run at a certain temp. Around 210-212 deg. Not like the old days when you put in a cooler t-stat, or removed it completely during summer.
You may have a t-stat that is stuck open.
This is what happens if your car is not running in the proper temp range.
If not running at proper temp, the cooling fans do not come on, this will cause the pcm to throw a temp code, this will cause a default and the A/C compressor will not come on. As you stated, you could use a jumper to get the compressor to come on. This may be something to consider, as I had pretty much the same issue on my 01 3.8.
If you have a friendly dealer around that will scan your car for free, or a mechanic that has a good scanner, have them check for a coolant code. If you are showing a coolant code, it might be as simple as replacing your t-stat and clearing the code

 

what switch? the switch in the controls or something else, like where the clutch enguages on the compresser

 

This will help thanks I do have a problem with my tempature gauge so that might be it. I appreciate the help

 

The Clutch does not seem to engage the compressor I was hoping when I popped the 134a in to the Low preasure outlet that it would create enough preasure that it would engage the compressor but no power goes.

 

I was wondering if you had resolved this issue. I just had my condensor replaced and still no AC. AC works fine when powered directly. Thanks.

 

Old thread alert!

You may want to PM the OP, but since he has not been on in over 2 years and has only 3 posts, doubtful he'll respond.

BTW - I believe I saw your post about the compressor. It will NOT activate if it does NOT have freon or enough freon. I've seen systems with little to no freon, turn the A/C full blast and the compressor does not kick in UNTIL enough freon was introduced during the charging process.

 

Thank you, I saw the original post date and I emailed the original poster. I was just excited to see that I was not the only one with this problem. I am at my wits end! My mechanic was working on it for 8 hours yesterday, he replaced the compressor and filled it with refrigerant. he knows about the low freon switch and said that it was full. I'm just trying to avoid a trip to the dealer.