Trouble Shooting AC

Ok, now that I've made a bit of headway on my 4 wheel drive, I've decided to get my AC fixed. Since, I'm a novice and don't know much about AC repair, I figured I would troubleshoot here so I don't get taken at the garage. Anyway, this is what I know:

1. There is a leak somewhere in the system, because there was very little 134a in it when I did a pressure check.

2. I filled it up with the big replacement can last night and checked the pressure today and noticed it dropped. (This stuff had stop leak in it)

3. As I was filling it up, the compressor never did come on.

4. I pulled the wire that goes to the Silver cylindar (not sure what it is, but it is in between the high and low side valves and has a female 2 pin wire that goes to it) and connected the wires together with a paper clip and the compressor turned on. So, I was thinking that the compressor is not broken, but it isn't getting a signal to turn on.

Anyway, I would appreciate it if someone could give me some pointers on what to do next. Maybe all I have left is to take it in. Any help would be appreciated.

Thanks, Mike

That silver cylinder is called an accumalator and the wires that hook to it go to a pressure sensor. If the compressor turns on when you jump the wires there is either not enough pressure in the system or the pressure switch is shot. Another point to be taken is that you should never add freon to a leaking system (just quoting the back of the can) and if the system is low you should have it evacuated prior to filling the system to get all the contaminants out of the system (moisture and the reguar atmosphere)

Thanks for the input. I didn't know the system had a leak until after I added the refrigerant. At first, I thought it just needed a recharge. I didn't put more in since I realized it was be leaking somewhere.

By the way. Can I rule out that there was not enough pressure in the system, because When I added the refrigerant to the system, the pressure was in the correct range. Shoulden't this have kicked on the compressor?

thanks for the reply