I am going to convert the AC in my 1992 F-150 4.9L from R12 to R134a. I plan to change the compressor, the drier and all the lines. Will the parts from a 1994 F-150 with 4.9 L fit the 1992 F-150? From what I can find, the compressors are the same (except for the oil) so the big question is whether the other parts will fit. The AC didn't fail, so the condenser and evaporator are fine.


Fred

 

Yes, they will fit. You might also consider changing the condensor while you are at it. R134a needs about 50% more condensor area that does R12. Oh, yeah, you need a red orifice tube as well.

 

Thanks. That's good news. It won't be that big of a job since the hoses all fit. Does the larger condenser also fit without any modification? Also what is the difference between the red and the blue orifice? I see them both listed for both years. Someone mentioned a variable orifice would be even better. Would that be a good substitution?

 

JAS88 - A couple of more questions. Do I have to flush the condensor and evaporator? The system was working, but I had a small leak and needed to add Freon every 5-6 months. Also if I do flush them, will denatured alcohol work or do I need a specific flush solvent? Finally since I will have removed all or most of the mineral oil that was in the system, is the oil that came with the compressor enough? I haven't measured it yet, but expect to find around 7 oz.


Thanks.

 

I am following this cause I need to redo my 1993

 

Stay away from the variable orifice type. You want the red orifice tube and not the blue. The blue is for r12.

I would only use an approved AC flushing solvent. Some have used brake cleaner. Remember, it needs to be clean and zero residue left.

Stay away from PAG oil. Use Esther oil. I think it's 8 oz. There is some difference's between '94 and '95, but I think 8 -10 and 32-38 oz of R134a.

I've also included a pic from a '95, F150 for the AC charge/oil amount. This is with the larger r134a condenser, not the earlier r12 version.

 

Whenever I have converted mine, I basically changed the orifice tube, put new lines on, as the old ones were leaking in the first place, and changed the oil in the compressor. With a larger condenser to start with, there is no real need to change it- and no need to do most of the stuff suggested. Leaving the original condensor may not allow it to get quite as cold, but it will still do the job.

HOWEVER- DO NOT JUST VENT THE LINES TO REMOVE THE R-12! This can net you a HUGE fine should you get caught... Take it to a shop, and have them properly evacuate it using a recovery machine. THEN do the work you want to, take it back and have it evacuated AGAIN, then install the new stuff. Done this a few times in the old days...

Scott

 

are the 94' condenser fittings different from the 93's?

 

My truck is a '91, so things may not be the same, but I had to have a special liquid line made (the hose that goes from the condenser to the evaporator) because the fittings were different. Not a big deal if you have someone locally, as I do, that makes a/c hoses.

If you are replacing the compressor, hoses, and condenser, the only thing you need to flush is the evaporator, you can flush it with AC solvent as recommended, and compressed air. Take it out of the case so you can tip it over to get all the old oil out before flushing if you can. It's not super-critical in my experience to get every drop of old oil out but the more you can remove, the better. Converting to R134a is like painting a car - the more time you spend on prep work, the longer the job will last.

 

BTW- You can buy adapter fittings for the R-12 lines to adapt them to R-134 when you convert the system... They simply thread onto the R-12 fittings, and have built in sealer with locktite...

Scott