Rebuilding/upgraded A/C from scratch

As a younger man, i could handle the heat a little better, but nowadays I am having trouble coping, and as such have come to the point of rebuilding the a/c system on my 92 2doorxj. The jeep originally had a/c, but when I added the russ pottenger 4.7, Everything removable was removed for simplicity. Now its time to check the youthful ego, and put stuff back for comfort.

How would you build an a/c system in a 92 xj straight six?

Obviously without stock restrictions, this is 2015, is there ways to do this better? I have no problem modifying stuff.

Would you use later model xj parts for simplicity/better parts?

Any recommended sources?

Thanks :

My '92 XJ had all the stock A/C parts about 6 years ago. I recharged it with R12 that a guy local to me had. A/C worked wonderfully.

Honestly, I would just reuse all the stock parts and switch to R134A ports. IMO, the stock A/C system worked very well and I had no issues with it so I don't see the reason for an upgrade.

xcm said:

Everything removable was removed for simplicity.

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What parts do you still have? Expansion block and evaporator core only? Were the lines blocked off?

Our Comanche is an 89 with a 1995 xj motor in it. The system was gutted by the PO. I went with this systems because the compressor bolted up to the mount we already had and was R134a. Bought every thing through rock auto except PN:55037203 I found on Amazon.

The AC system I think is the same for 1993-98 cherokees with R134a.
Compressor PN:4717005 replaced our old PN:55036697
Condenser radiator PN: CH3030151
Dryer, receiver, Accumulator PN: 0233562
Expansion Valve PN: 3411290

Hoses
PN: 56831
PN: 56830
PN: 56834
PN:55037203 (Accumulator to Expansion valve)

Only part we didnt buy was the evaporator in the dash which is OEM 1989 and worked with the 1995 expansion valve.

The last hose was hard to find and didnt know we needed it (amazon).
It was surprisingly difficult to make this kit ~$500 in parts

MoparManiac said:

Honestly, I would just reuse all the stock parts and switch to R134A ports.

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Does the new refrigerant cause issues with the older system? Does it require any mods to work?

convert to 134a. R12 is impossible to find.
if you're using r12 components, You can easily convert, just check you tube. you'll need to convert the hi and low pressure inputs to 134a-- you can either weld on new ones or they have pop on adapters. you'll need to completly drain the system, take all the oil out of the compressor (r12 oil is incompatible with r134a), and refill. I'm running a r12 compressor w/ 134a --- works great, cold as ice. Only issue is that you can only fill the compressor to 75% of original capacity -- r134a expands more than r12 -- if you fill it to manufacturer's recommondations, it'll destroy the compressor (at least).

I went through this when rebuilding mine-- seriously was not a huge deal. But whatever you do, I highly recommend staying away from r12. It's virtually impossible to find, and when you do, it's crazy expensive. And when you first build your system, you have to expect to go through more than just a single recharge -- you're inevitably going to have leaks the first time you put everything together.

My AC currently kinda works. It doesn't always blow ice cold, so I was thinking about having it refilled with 134a since r12 is banned now. Wasn't sure if I could just dump 134a into the system after evacuation of remaining r12 and oil.

you would want to have it evacuated and probably change the accumulator to ensure the system is compatible with the new refrigerant and the new oil.

This conversion sounds easy peasy. Also sounds like a good cool weather project.

Compressor oil is carried by the refrigerant. R12 and R134A use different compressor oils that are incompatible with the other refrigerants. So at a minimum, you need to remove as much of the old oil as possible, because its not going to recirculate. That means replacing the drier/accumulator (where oil pools up). Some people also replace the condenser and evaporator cores, some people just try to flush them (hard to do), some people just ignore those components (I replaced them on my Jeep because they were rotted anyway, but I didn't do anything on my old Cadillac). Another factor is that new R134A systems uses different o-ring material, and you can replace those if you want (easy to do if you are rebuilding anyway). The more you do the longer the system will work well.

How hard is it to replace the condenser and evaporator cores?

Could I have it evacuated, replace the drier, have it refilled with a small amount of 134a, run it for a few days, have it evacuated, then fill up with 134a?

bigalpha said:

How hard is it to replace the condenser and evaporator cores?

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Condenser is pretty simple, its in front of the radiator, just remove the header panel and there you go. Evaporator is inside the dash with the heater core, not so easy.

Could I have it evacuated, replace the drier, have it refilled with a small amount of 134a, run it for a few days, have it evacuated, then fill up with 134a?

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Should work fine. Ester oil is compatible with both refrigerants, so if there is any chance that there is any old R12 in the system then you need to use ester. If you are replacing everything for a full conversion then you could just go ahead and use PAG oil.

Great info, thanks! I think that the Evaporator will stay as-is and I'll just replace the condenser instead.

Is there any regular maintenance that needs to be done on the stock AC system besides making sure the condenser is cleaned out? Trying to eek out any last remaining performance out of the AC to finish off the summer this year.

Its a closed system, nothing to maintain if its working

Yeah that's kind of what I thought, but wanted to double check. Thanks!

Well, you could put a larger AC compressor from a 93-98 Grand Cherokee in there. I'm not 100% if you can use the entire accessory drive from a ZJ and use the OEM AC bracket or if you need to modify the XJ bracket but I know the bolt pattern is different.
The Cherokee had really good AC in stock trim as long as everything was working / charged correctly. You could strip down the interior and add insulation / noise dampening under the carpet & in the headliner & doors to keep the cold in the jeep, though.

Adding noise dampening is definitely something I'd like to do at some point.