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The summer is starting to get warm here in NC and its time to figure out my AC.

MY 81 Wagoneer came with the factory AC unit mounted under the dash. The fan blows fairly well, but I was wondering how cold it will actually get. I have to replace the condenser/dryer and lines anyway. Is it worth replacing those parts and charging or is it worth it to just go with an aftermarket from someone like old air or nostalgic AC?

If it works why mess with it. if you want it to work well you must charge it with R12, R134a WILL NOT COOL NEAR AS WELL. I know you can red where it does but it does not. this is why many owners of old A/C systems think they need a new set up.

I am working on my factory A/C right now. 440 is correct about the R12. If you can find a shop that will work with it and get you hands on some, that is the way to go. We are going to charge mine with 134a to check for leaks, if we don't find any, then we will evac that and replace it with some R12. Have heard from many here that R12 in our factory systems blows ice cold.

While I will agree r12 works better 134a works and blows cold in my system.

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+1 I still have working R-12 factory air and it works great, it is ICE cold and I will not change it!! If it can be charged, this IS the best way to go!!! IMO

I have a 77' Cherokee with factory air. The only part that is not stock is the compressor. It's a Ford FS10. It will work well up to about 102°. Was 101° degrees yesterday and it was doing fine. I run 134a. The biggest problem I have is the evaporator core freezing up when it is humid outside, and the housing breaking. It is 41 years old after all. You will be fine with 134a.

Maxi fridge, have it in my 92 chevy, compatible with r12, it's a butane gas mix. It gets too cold, as in humid areas it will freeze up the condensation.

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cool. better news than I was expecting.

One more question though. I swapped in a 5.7 TBI vortec for the straight 6. With it came the GM AC compressor. Do you have any idea if I need to wire up an on/off switch to get the compressor to kick on? I also have a compressor off of a 83 wagoneer with the 360.

I converted my 79 chiefs system to 134a. Everything under the dash is stock. Everything in the engine compartment is new. I use a York to Sanborn adaptor kit to mount a Sanborn unit and pitched the York. I used Classic Air for the Sanborn adaptor, the hose kit, which comes with multiple fittings for different sceneros and had to outsource to a Farm Parts supplier for a special flare fitting to hook up to the evaporator. Also used Rock Auto and other sources for the condensor and dryer.

To answer your question, your fan switch on the underdash unit should turn on the compressor. Hopefully your compressor has only one wire. I wired mine with a pressure switch that I added to keep the compressor from turning on if the refrigerant was low.

Markstrimaran wrote:Maxi fridge, have it in my 92 chevy, compatible with r12, it's a butane gas mix. It gets too cold, as in humid areas it will freeze up the condensation.

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Yea ive used that r12a stuff aka the butane mix in the wagoneer.. although it says its not compatible with butyle hises.. not sure why.. but when i had it in the compressor kicked on and damn it was cold lol.. i used it until i found aomeone with a large supply of r12 and then i just let all the butane out and we put the r12 in.. Seems my r12,xharge is holding for the 2nd year... when im moving yhe a.c vents get so cold my knees and shins start to get numb lol.

Mine was just fixed and retrofitted for 134a...I just attributed it to being a 28 year old vehicle. Did not think of the R12 deal....still works okay

I found a shop that will charge mine with R12. We'll see!

Just hope it doesnt have a major leak. The old compressors were known for leaks aparently.. Thats why the 89 up models had new compressors. I think it was 89 and up.. zbut my 90 has a better style compressor on it

I have four old cars with different types of A/C systems that were all originally R12 and now converted to R134a. All the service manuals have specific test procedures for performance checking the A/C systems. They specify a certain vent air temperature given a certain ambient temperature and other conditions.

Every one of my converted R12 to R134a systems meets or beats the original performance specifications. These systems are not just converted, I fully rebuilt the entire systems top to bottom when I converted them.

I just think old car owners often have this attitude about "everything was better back then". Refrigerant, gasoline, oil, women, politics, segregation, the world... They get caught up in that. Plus the fact that the R12 to R134a conversion is usually done by people who frankly don't know what they are doing and cut corners by not fully rebuilding the entire A/C system in the process.


The systems in FSJs are especially forgiving of the kind of refrigerant in them because they use an expansion valve to regulate the refrigerant flow. The expansion valve does not know or care what refrigerant is inside the system. All it cares about is the evaporator outlet line temperature and it will regulate the flow of refrigerant neccesary to maintain the temperature of the evaporator outlet. If the refrigerant is less efficient, it will just flow more of it to achieve the sam temperature. Orifice tube systems are a little less forgiving but no FSJ has an orifice tube so we don't have to go there.


Generally if your Cherokee or Wagoneer air conditioning will keep the interior of the Jeep 20 degrees below the outside temperature while you are driving 50+ MPH, it is performing as good as it is capable of. Any speed below 50 MPH will significantly reduce A/C cooling. You might as well turn the A/C off at idle. These are a large interiors with a lot of clear glass and are hard to cool. The trucks do better and darkly tinted windows help a lot.