Hello all!

Quick question, I couldn't find this anywhere else... so.... I believe that 94 and higher XJ's used r134, my 92 used r12. I want (need.. I live in SC) to reinstall a/c on my jeep. So. My question is this, would the entire A/C system from a 94 bolt up? Or would I have to modify it somehow. Keep in mind I would have to buy everything BUT the evap core new anyhow.

Thanks again, all!

 

If I remember correctly, all you need for a “retro fit” the R12 system to the R134A is to install the updated fittings onto the ports, which are just screwed on, make sure the oil is compatible with the system, and refill as necessary.

Best way would be to update some parts, like the dryer and compressor, make sure all the R12 is evacuated, install the new fittings, fill and enjoy the cool air.

correct me if I’m wrong.

 

You are correct. However, some seals don't react well between the two refrigerants, and I have to buy all the stuffs anyhow, just checking to see parts similarity.
SO, I am getting ready to buy a compressor, condenser, dryer, hoses and expansion valve.

 

Hopefully someone else chimes in then, I’m sure it shouldn’t be too complicated or huge differences. The only thing that’s bothering is that since these systems have an accumulator, there should be an orifice tube inline not expansion valve?

Anyways wrench on

 

You need to replace all your O rings, which probably need it anyway. You need the green ones. Also replace the filter dryer, evacuate the system and add r134A compatible oil to the system, then charge it up. Most folks don't replace the oil, but it really needs to be done since the R12 oil is not supposed to be compatible with R134 oil. Some of the new oils are OK with both

 

You could use Enviro-Safe hydrocarbon refrigerant, which will work with the existing oil and seals in an R12 system, and actually provides better cooling:

https://www.es-refrigerants.com/prod...ment&Trying=ON

It is now sold as an "R134 replacement" due to federal regulations, but it works perfectly as an R12 replacement. (In fact the same product was originally labeled "ES-12" years ago and marketed specifically as an R12 replacement.)

As far as legality, at the federal level as far as the EPA is concerned it is permitted for use in R134a systems, or older systems that have been previously converted to R134. You'd have to check state and local regs for legality in your jurisdiction. This product is flammable, so you need to use reasonable care (no smoking!) while working with it. Also, NO SHOP will touch your AC system if it has this stuff in it, or anything but R12 or R134. (Well, there is also a new refrigerant out there but you won't be using that.) You would have to commit to working on it yourself.

Another possibility of course is to stick with R12. It can still be found (old stock or recycled), but is expensive.

The standard option of course is R134 conversion. R134 reduces cooling capacity by about 20%. Most domestic US vehicles have sufficient capacity that this is not too much of a problem. You need to flush all the old mineral oil out of the system since it is not compatible and replace with Ester oil. (Otherwise you risk the dreaded Black Death - catastrophic lubrication breakdown causing compressor failure and severe contamination.) Also you would need new O-rings and a new receiver/drier compatible with R134.

 

If you are buying practically all of the parts new, you should be fine. Use the proper O rings and flush the evaporator real good. Put it all together, vacuum the system to check for leaks and remove any moisture. Then charge it up and enjoy the cool air.

 

If you go with 134a, there's a difference in the receiver dryer ...has to do where the oil hole is located. I can't remember now, I'm a little fuzzy on it. I blelieve the hole for the 134a hole is at the top and the 12 hole was at the bottom. Makes a difference how the oil is picked up. If you're switching refrigerants I would remove the compressor and either buy a new one or remove the lines and pour the oil out and flush it as best as possible. I've had compressors apart for rebuilding and they hold a lot of oil. It's almost impossible to get the oil flushed out while it's on the vehicle. Mineral oil and Ester oil are different, different properties. Yours probably has mineral oil in it. Plus, at the age of your rig, the front pump seal is probably weak anyway. That's probably the number one location where leaks develop. The smart money is to remove all the parts and flush out ...buy a new receiver/dryer and pump and o-rings. Then you won't have to screw with it. Find someone with a vacuum pump and pull a tripple vacuum on it (that's 3x times!). That's what it takes to remove all the air. You know ...if you bought all the parts, it might just be easier to have an a/c outfit swap it all over and flush (with their flush system), pull a vacuum and fill it to the right level ..and do it 'right'. They don't charge that much. Good luck!

FWIW, I had a truck converted over and they strongly suggested I replace the compressor. I didn't out of funds at the time and it lasted about all of a week! But by then I'd pumped mineral oil all over the place and needed to be re-flushed. There are videos on youtube on converting.

 

No orifice tube.

My 95 has a factory R134a system that is comprised of the compressor, condenser, evaporator, expansion valve, receiver/dryer and the hoses. As I understand it this is the same setup they used for the R12 systems.

If you're not pulling your dash apart to replace the evaporator, take EXTREME care when you remove the old expansion valve block so as not to bend the hoses coming out of the firewall from the evaporator. It is a PITA to get both of those f'n lines to screw into the expansion valve block if they are not properly aligned. Ask me how I know.... lol.
Harbor Freight sells long length 3/4 and 7/8 wrenches (I think I paid $20 for the set) that I found invaluable for dealing with the threaded fittings.. in your case since you're replacing everything they may be a luxury item rather than a necessity.