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R12 to R134A Conversion


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Alright, I admit an A/C idiot and I'm not ashamed.  :rotfl2:  My original R12 compressor seized up, and I'm going to  convert to R134A refrigerant since I'm out of R12. I already have a NOS R134A compressor I picked up a few years ago as I knew this day would arrive sooner or later. What other A/C parts do I need for the conversion? My plan is to install everything I have to, then bring it to a shop for charging.

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You need to replace the receiver / drier , which is the cylinder located by the alternator with the sight glass on top of the cylinder . You also need to replace the expansion valve which is the block located where the 2 AC hoses connect at the firewall .Buy some AC flush before putting the new parts on and pour the flush in the rest of the AC system , follow the directions as to how long to leave the flush in then blow it out with an air gun . As far as the new compressor goes it will have a small amount of oil in it but not enough for the entire system and you or the AC shop will have to add more . When replacing all the orings make sure you coat the orings with the PAG oil ( refrigerant oil ) . The AC shop will run a vacuum test to make sure it does not have a leak before filling with refrigerant and PAG oil.

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Yeah, I forgot about the dryer. Valve and dryer are fairly cheep though, under $20 each at Rockauto.

 

As for the hoses, you'll find no problem locating the hoses for the 4.0, they don't exist for the 2.5, however, I see little difference in them. They are expensive, IIRC.

 

I contacted Jeep Air in FL at the time and they told me to use my existing hoses, that the 'barrier hoses' were a nonsense ploy to sell new hoses.

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When my compressor went belly-up 5-6 years ago (seals were shot and refrigerant was gone), I bought the equipment to do the whole project myself. I stuck with R-12, because I, like you, had purchased a 15 lb. can of R-12 back when one still could. I replaced the compressor, receiver/dryer, expansion valve, and all the hoses. If I recall correctly, I also replaced the condenser, though I don't remember why (it shouldn't be necessary). I had a flush canister to flush the evaporator core (everything else was new), and blew it out with an air gun, then put it on a vacuum pump for 30 minutes to ensure that the system was completely dry, and filled 'er up with R-12. The vacuum pump and R-12 canister hooked to the system through a manifold with gauges. Haven't had to touch it since. If you still have the original 24 year-old A/C hoses on there, I would recommend replacing them, along with the filter/drier and expansion valve. I would guess that I still have about half the canister of R-12 left if I ever need it.

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