Adding A/C?

Has anyone added a/c to a factory non a/c truck? I'm getting ready to try, it's just too darn hot here in TX.

I will be adding the a/c to my 1988. I have a 1989 4.0L with a/c for parts and I also have a heater, a/c box and compressor from a 91 4.0L. Is there any chance that all the wiring is there in my 88 or am I looking at swapping in all the electrical harnesses from my 89?

I am going to start pulling the dash out tomorrow after work.

I'm getting ready to do the same thing. Keep me posted on your progress...Scott

I know its been a while since I first posted this thread, but I finally got around to this project. I currently have my dash taken out, the old Heater box taken out, and the new Heater A/C box installed. What a huge PITA! I will continue to update this thread when I make some progress.

I did this last year on my 87 2.5. Most of the wiring was already there. The HVAC box had a seperate harness that in mine plugged into an existing harness connector somewhere in the vicinity of behind the radio. The connector had all the wires in it already on one side and didnt have the unused oneson the original heater box. I plugged it up and all was well on that part. In the engine compartment though was a different story. The compressor wire was there already, but the relay and control wires were not there. There was an unused connector in there though that was saved for "dealer installed AC" I found it listed in the downloadable Factory service manual, and made up the relay and harness I needed to get it all to work right. I'm not sure if any of that would be the same for the 4.0 or not, but its worth a try. Be sure to open up your new HVAC box and clean it out while its out... check the evaporator and heater core for leaks, and replace as necessary. I sprayed the hell out of mine with Lysol because it had a mouse nest in there. Cleaned the nest out, cleaned the box up and sprayed it till it was soaking... let it dry, re-assemble, and hook it all up. Good luck!

I put a heater A/C box in from a 1991 comanche. The A/C thermostat has a 3 wire plug, and my harness has a 2 wire plug.

Any ideas on how I can make this work?

Does anyone have a harness from a 1991?

Wow, back in the day, when we bought our '87 new, it didnt come with AC so the dealer installed it for $870+/-. I didnt realize it was that drastic to put one in.

Do you guy's think I can make the 91 A/C box work with my 88/89 wire harness?

The 91 has 3 wires and my harness has 2.

Well I have decided against using the 91 a/c box. So, today I replaced the 91 a/c box with the one out of my 89. I have now removed 3 a/c boxes and installed 2, and I have to omit that it is getting easier. I have everything wired and ready for the dash to go back in. I will be hooking up the compressor tomorrow and start trying to figure out all the wiring under the hood. When I am done, no one should be able to tell that the truck didn't come with A/C from the factory.

I would like to jot down several of your infos. My uncle bought a used 90 Comanche without A/C and last I heard he'd been planning to install an A/C.

I did this last year on my 87 2.5. Most of the wiring was already there. The HVAC box had a seperate harness that in mine plugged into an existing harness connector somewhere in the vicinity of behind the radio. The connector had all the wires in it already on one side and didnt have the unused oneson the original heater box. I plugged it up and all was well on that part. In the engine compartment though was a different story. The compressor wire was there already, but the relay and control wires were not there. There was an unused connector in there though that was saved for "dealer installed AC" I found it listed in the downloadable Factory service manual, and made up the relay and harness I needed to get it all to work right. I'm not sure if any of that would be the same for the 4.0 or not, but its worth a try. Be sure to open up your new HVAC box and clean it out while its out... check the evaporator and heater core for leaks, and replace as necessary. I sprayed the hell out of mine with Lysol because it had a mouse nest in there. Cleaned the nest out, cleaned the box up and sprayed it till it was soaking... let it dry, re-assemble, and hook it all up. Good luck!

Thanks for this well detailed post. Will jot down infos if you don't mind.