john89gt

1992 Mustang 5.0-System was R12, so I'm converting to 134. I vacuumed the systems and filled with 134. The compressor will cycle for a second or two, so I'm assuming maybe its good? It's only blowing hot air in the car and my friend helping says the 134 is not flowing through the systems. Before I just started throwing money at it, I thought maybe I would check with the experts and get some insight. Any thoughts on where I should start? Accumulator, Orifice Tube, or any thing I could check on the car? TIA

dawson1112

IF you did the conversion, take it to a certified ac technician who can put some gauges on it and check the pressure. A good tech will be able to tell exactly what is causing the problem by comparing readings between HI/LO sides. If your sure you have the correct amount of refrigerant in it, then its most likely plugged some place and that means that its probly getting dagerously high pressure on the high side.

john89gt

Thanks. Yes I can always take it to the shop, but I thought maybe I could chase down some of the small things before resorting to the A/C shop. Sometimes it may be something small that got overlooked. I was just trying to get a few different opinions on the matter and appreciate yours. It has the right amount of refrigerant in it. It was vacuumed down, two cans of 134 and ester oil added. There was a set of gauges on it while this process was being completed. No other immediate problems other than it not cooling.

Derf00

You should keep your threads to one-per-problem:
https://mustangforums.com/forum/5-0l...-a-c-help.html

A self conversion is almost never done right. Not because you don't know what you're doing but because the "conversion kits' they often sell are incomplete or incorrect and if aren't familiar with AC, can/will lead you down the wrong path. Read my response in the other thread.o

john89gt

Derf00 , Today 03:07 PM
Converting from R12 to R134 is not that easy.

Besides the obvious high/low side valve size differences,
- You need a new compressor (R134 runs at a higher pressure than R12 and the seals are not cross compatible) SO, even if it works for a bit, it will blow out the seals on the compressor.
- ALL of the o-rings need in the system need to be replaced or you will get a leak.
- You also need to replace the receiver drier and flush (not just vacuum) the AC System. R12 uses mineral oil for lubricant. R134 uses PAG (a synthetic oil) for lubricant. They are not compatible with each other and R134 will not carry the oil to where it's needed so you will end up burning up your compressor even if it does fire up and that's if a leak doesn't happen first from the wrong o-rings or wrong oil.

Start over.


Derf00-Thanks. And as for my “threads,” I realized it was in the wrong section so I moved to where I thought it should be. If I knew how to delete it at the time I would have. As for the A/C, your help is appreciated. This car is not a daily driver and I own three Fox mustangs, so I wasn’t really trying to sink a bunch of money into this one. With that said, I understand you get what you pay for. I have read a lot of threads on here and it seems people have pretty good luck just vacuuming down the system, then adding Ester oil/134. I was thinking maybe mine had a blockage in the drier/accumulator or the orifice tube. What would you recommend to flush the system with?