Brett Jenkins

I searched and found many discussions on r12 and r134, but nothing to answer my specific question. How do I tell if my system is still r12, or has been converted to r134?

Bill Ball

R134 would have larger fill ports, usually put on as adapters to the original smaller R12 ports. If you see R12 ports but are still suspicious for some reason, AC service shops can test a sample. If the system is not charged, you should have it flushed, the compressor removed and drained of oil and the drier replaced, then the proper oil installed for whatever R you use.

douvillier

An AC shop will have a machine which will tell you what type of refrigerant you have in your 928. Don't go by what fittings you have on your lines, someone could have done an incorrect conversion. Since you have a 928 with the electric fans I would convert it to 134. R134 operates at higher pressures therefore higher temperatures. The dual electrical fans removes the heat better than the older single fan engines. If you convert, you will have to evacuate the system, replace the receiver/dryer, suggest replacing both shrader valves (big source of leaks) and draw a vacuum on the system a mininum of 45 mins. There is a TSB on conversion from r12 to r134 that will tell you how much oil and refrigerant is required. I would stay away from any other type of refrigerant other that r12 or 134 as a shop will not touch your system if you have an " exotic" freon.

IcemanG17

Since the price of R134 has climbed quite a bit.....& 928's were originally designed for R12...plus R12 works better at lower pressures.....I would stay with R12......a properly running R12 system should get temp differentials of 50+ degrees!! I've seen low 20's at the center vent (70ish degree day).....

You do need to take it to a shop to determine what type of coolant you have!!