Hi haven't posted in a long while..
I am trying to locate the wires to jumper to engage the a/c compressor clutch (not fan clutch) so I can add coolant/get a reading.
About 3 years ago I replaced the compressor and dryer and changed over to 134a ya,ya I know big mistake. Anyway all was fine until about a month ago one day it was ok the next day I took a trip on the freeway (about 45min) and it was blowing cool-cold air but not really cold like it had before.
Finally, I bought some good gages and tested it. I really wasn't exactly sure what I was doing and released some of the refrigerant. Now where I'm at is the pressure is too low to engage the compressor to add coolant or get a reading. I was reading its OK to jumper the switch to engage the compressor to get a reading and add coolant so this is what I am after. If you have a different suggestion to solve the problem please say so I will surely appreciate it.
The A/C on this truck never really cooled very good at low or idle speeds but I think I recall reading here this was a common problem others had. If you have solved this please let me know.
These darn gage's are a pro set but really did not come with much instruction (Harbor Freight). If anyone can comment on their use or direct me to a site I would appreciate it.
That's about it for now, lots of questions sorry. BTW you guys here have helped me out several times and I truly appreciate it, I'm sure this question has been asked before here <img src="/forums/images/graemlins/angry.gif" alt="" /> but I just DO NOT have any luck with the search for this forum.
Thanks for your help
1990 Trooper Ls
V6 2.8L 5pd

IIRC you can just supply 12v (and ground) to the 2 blade connectors behind the clutch to engage it. I don't even think polarity is critical, as long as you DISCONNECT the wiring harness connector that goes to it first. Maybe check around a bit more before trying that, it's just what I remember reading somewhere.

ON THE LFT FRT CORNER BEHIND THE GRILL IS THE PRESSURE SW, ANYTHING BELOW 30 PSI IT OPENS CIRCUIT TO PROTECT THE COMP,YOU SHOULD BE ABLE TO JUST PUT THE GAUGES ON BOTH HI AND LOW SIDE OPEN THE LOW SIDE VLV ONLY, AND LET IN ENOUGH REFRIGERANT TO GET THE PRESS UP TO 30-35 PSI AND THE COMP SHOULD KICK IN, AND THEN PUT IN THE CORRECT AMOUNT OF R134 , BE CARE FULL AND DO NOT FILL UNTILL THE SIGHT GLASS IS CLEAR , IT WILL BE WAY TOO MUCH, FILL TOO 80 % OF THE R12 FILL, OR YOUR PRESSURES WILL GO TOO HIGH AND AT ABOUT 340 PSI THE SW WILL OPEN AGAIN, JERRY

Didn't even think of just adding enough to kick it on <img src="/forums/images/graemlins/rolleyes.gif" alt="" />..good tip. I will do that then I'll be able to check it with the gages. <img src="/forums/images/graemlins/kewl.gif" alt="" />
Thanks. Thanks for both replies I appreciate it. Right now its been in the low 90's be the 100's are coming back soon <img src="/forums/images/graemlins/angry.gif" alt="" />
J.P

If it is dry it might take a can or 2 to get it to start cycling. If your using a parts store setup with a gauge on the line don't use the gauge. Just add enough so that the pump stays on then stop. I blew a pump in my ramcharger going by the gauge on a Advance auto DIY kit.

Converted systems using R134 usually need more airflow over the condenser. I added a 10" Hayden fan to my 90 Trooper, it makes a big difference at idle and low speeds.