Installing air conditioning on a 91 XJ with no a/c ...

I've got a '91 with no factory air. I want a/c this summer.

Anybody ever install a/c on a jeep with none? I've got a guy at a local junk yard who said he would sell me *all* the a/c-related stuff on a wrecked XJ for $50.

Another option is to get an after-market unit.

Anybody have any experience with any of this? Any advice?

Thanks.

The tough part is putting the evaporator in the heater box, whole dash has to come out and while it's out I'd use a new one and replace my heater core at the same time...sure as god made little green apples as soon as you put it back together the old will spring a leak..

Do you know if the heater box is the same on vehicles with or without a/c?

I don't know jack about a/c. Can somebody list all the parts I'll need? Thanks!!

Hmm, off the top of my head, condenser in front of radiator, hoses to compressor, compressor & fan clutch, brackets and idler pulleys as you fan belt path will change, drying tower and hoses to that, evaporator inside heater box, slider control and cables, not sure about the box itself.
Might be easier to have the donor sitting next to yours as you work. Pay special attention to how the evaporator seals against the firewall. There might also be a drain involved and a hose associated with that too, thats under the passenger side carpet where you feet go...fuses, relays and wiring too.
It's do able and if you really haulbutt maybe a weekend but it will be a long weekend, the dash/heaterbox is 8 hours alone....

Thanks, RichP. I went over to partsamerica.com just to look at what parts are listed for a/c ... and there's also the Aux. fan on the radiator where the a/c condenser goes. And it will need a switch to turn it off and on.

Anybody know how I can get that going? Where does the switch go, and how does it work?

Also ... is the heater box for a/c XJs the same as the heater box for non a/c?

Thanks for any help you can provide.

The "switch" should be provided by the ECU, when it gets an "A/C request" signal. If that doesn't work, an auxiliary switch can be provided to energise the relay.

Question - do you have the idler pully that replace the compressor? If you do, could I have it if/when you do the job? I could use another one (and I'm sorry I can't be anymore help.)

5-90

Just completed installing AC into my 88 Jeep Comanche that did not have AC before. It is actually quite the job because of the heater box install under the dash (looks easy but its not). You are more than welcome to PM me for more questions or pics. The things you will need are: Heater/AC box from a vehicle that had AC because there is a drain valve at the bottom for condensation, all hoses and connections from the engine compartment, new in cab control for AC with wiring harness (very important), condensor (in front of the rad) and dont forget the temp sender, new compressor and receiver/dryer (these two should be new because it is almost impossible to clean them from R12 to add 134 or Freeze 12), aux fan (I prefer the 97+ for more air flow), and try to find the wiring harness for relays and fan (I made my own) but it would be easier. Dont forget the switch to the receiver/dryer like I did. You do not need a different pully or belt - just remove the idle pully and the compressor just fits right on with your old belt. The most difficult part is removing the the heater box without removing the dash - but it can be done. The other difficult part was the wiring. I made my own harness but some of the wiring was different than the service manual wiring so this made it a little confusing. All in all this install took me about two weeks with all the parts. The only dumb thing that I did was take it into a service shop to get leak cheaked and filled afterwards and they charged me $350! And there was no leaks! Dont do this. There are perfectly good safe kits to charge and test your system at the parts store. Best of luck!!!

Get a new filter/drier when doing this job. Its suppossed to be changed anytime the system is opened and exposed to air. The drier is a hydroscopic bag that absorbs moisture out of the system, if the system is opened up, the bag will absorb humidity out of the air and fill up, thus you should get a new one.

As well, the PAG oil used in R-134a systems is hydroscopic and will absorb moisture contaminating it. I'd seal up the compressor well, until the install, drain/flush as much of the oil as you can. Make sure you flush all the oil out of the other parts. That way when you service it, you just add the full capacity of oil, its the only way to make sure you have enough oil.

Too much oil takes away refrigerant and lower the cooling capacity, too little oil will let the compressor burn up, so more oil is better than less, but you want to be as close as possible to the proper amount of oil. Fresh PAG oil would be best, since any of the old oil coming from the system that was broken open and removed is most likely contaminated with moisture.

As well, if you don't have a good vacuum pump/source, I'd take the vehicle to a Professional to be serviced once its put together. Without a proper vacuuming down, there will still be air and moisture in the system, the air and moisture will form acids in the systems and destroy it. It is vital to have the system hermetically sealed, with nothing but refrigerant and refrigerant oil in it, no air or moisture. The new filter drier should absorb any tiny trace of air/moisture that remains after a proper vacuuming down and waiting 30 minutes for remaining moisture to boil out while at a vacuum.