i gotta ac problem /:

... you probably won't like it, but here's the bad news. Testing the clutch on the compressor with a jumper wire won't hurt anything, but using a test light to check anything going to, or coming from, the a/c control module, whether in the cab, or under the hood, is a bad idea. On our trucks, the volts going to the sensors, relays, etc. may only be something like 3 or 4 volts (it could be more or less, depending on the component). Meaning, there's not enough current to make the test light to, well, light up. And, if you have a hot wire sending 12 volts back through a system not designed to handle that amount, very bad things happen. In this case, a volt/ohm meter would have been the tool to use. According to my dad, you may have accidentally fried your a/c control module. He said that the a/c system can get pretty... complicated, and even the different manuals for working on the a/c doesn't really tell you how to go about fixing the darn thing, or what all to check.

Right now, your best bet would be to take your truck to a Mitsubishi dealership, and have them check it out. I know that's probably not what you're wanting to hear, but the a/c control module was probably bad in the first place, so no real damage was done. As I said, the a/c's on our trucks are something else, and for quite awhile had my dad pulling his hair out, especially since all the different manuals didn't tell him jack squat. He had to figure it out all on his own.
Sorry for all the multiple posts, but I'm on my PS3, and it only allows so many characters per post. Maybe a Mod couid condense it all together into one or two posts.
I hope you can get your air fixed soon, and, again, I apologize for being the bringer of bad news. :(

I sure wish I coulda linked found this thread..Its EXACTLY what my 95 mmax 2wd was doing..and it turns out same issue re system (it was a stopped up/clogged expansion valve...and based on what I got out of the system, and esp the exp valve, someone (dumb ass)! "sealed" a leak, and the big leak kept leaking, however the exp valve is clogged now, and compressor shot due to oil being forced out from high pressures from clogged exp valve...When I disconnected the evaporator, oil shot out, and more oil, until it lost pressure..4+ ounces at least.. OK I know why compressor is empty of oil now..AND compressor is for r 12, system, so back to re ordering and more BS and wasted time! Grr! Anyone on here got A/c contacts that are reasonable? Honest?

I am having no problems running my 87 r12 compressor in my 134 conversion. Clean it thoroughly and use 134 with ester oil and it should be fine. Mine blows ice cold air

Well... I have a 1989 2.0L Mitsubishi Mighty Max. Didn't have AC, managed to buy all the components. NEW- OEM Compressor, Condensor, Reciever, Expansion Valve, Evaporator, Pressure switch and got my Hi and Lo hoses replaced. Only bought a few things from the junk yard.. like, EVAP Housing, AC Button, steel/aluminum AC Lines, and a wire that connects to pressure switch... runs across front of Condensor hooks up to compressor and two other Blue connectors connect to two coming off my truck. There is one black connector that runs off of this wire I bought as well and I dont know if it is the reason why my clutch isn't engaging... I need HELP. My system was converted to r134A and hold refrigerant very good. But cant figure out with my brand new compressor isn't firing on... my pressurw switch is brand new as well...

see my response to your message.