Should I go with R12, R134A, or Envirosafe?

R12 will blow colder than R134A. I wouldn't mix refrigerants though, makes disposal much harder. R12 is also bad for the Ozone and that's why they don't sell it anymore.

well im gonna get on my soapbox here. the coldest possible is a term that is severely limited in its practicality. Ac systems work on 2 primary principals: temperature, and pressures.The pressures in R134a are higher than R12, and the system is sealed tighter. You want to keep the R134a conversion, because you havent flushed and cleard the system to properly use any other refrigerant. SO... Pull the system to a vacuum for about an hour, then close the valves on your gauge set for 5 minutes. The low side vacuum bars should be around 28Hg, and should not move. If it moves, there is a leak somewhere. Fix the leak and do it again. Then charge the system. Add 1 pound, then run the vehicle. Check the pressures. The optimal pressures you want are 30 to 35 psi on the low side, on a 90 to 100 degree day. The high side should be 100 to 150 psi over ambient air temperature. Which on said 90 to 100 day, should be 200 to 225 psi, 250 psi absolute maximum.The target temperature in the cab vents is 25 to 30 degrees colder than ambient air temperature. SO if you were to put a meat thermometer in your bents, the air should be 70 to 75 degress. IF after 5 minutes of run the vehicle, the air isnt cool enough, add small amounts, appoximately a 1/4 of a pound , until your pressures are targeted and so is the cab air. Now after you add the first pound, there are a few things to look for: 1..make sure the compressor clutch engages, and doesnt short cycle. 2.. make sure the low pressure lines cool off and start to sweat, and 3.. make sure there is no ice on the low pressure lines or on the evaporator. If any of these occur, then you have to diagnose and correct the blockage. As far as your buddies fog coming from the vents.. thats not good. He has a freeze up condition on the evaporator, and his Ac wont last long. You Ac system will only get so cold, it wont end up like a meatlocker in there, if does, then there is a serious problem.

Hope this helps

Your best bet is to sell the R12 to someone that is qualified to work on refrigerated appliances that still use R12.(mostly refrigerators) If you wanna go through the trouble of keeping an R12 system, then what happens down the road, when you have to have it serviced, this same conflict happens, only it gets way more expensive.....and it might be a deal breaker if you want to sell the vehicle. (the new owner will not want to eat that expense)

The R134a is a very good refrigerant. Automotive systems have been able to better utilize its performance characteristics since it was first introduced. Why do you think its used in every commercial ice machine?

You're buddy's F150 blowing fog means its got a problem......

I would ditch the crappy R4 compressor and bolt on a York and then I would make sure the system is sealed up tighter than Fort Knox, triple evac finishing with a 400 micron vacuum for an hour, then charge it up with the R12. If you want to do the 134a properly instead you need barrier hoses, double end cap PAG oil, and the biggest baddest parallel flow condenser you can cram in front of the radiator. Throw in an adjustable low side pressure cycling switch for good measure.

R12 might void the warranty on the compressor. Use R134a.

go with the 134a. its ozone safe (whatever that means) but its much more economical. you could even make some cash by selling the R12 to an appliance repairman or a/c repairman. as far as your buddys f150, he should get that seen about because it sounds like he has a buildup of condensation in his a/c unit. thats what makes it fog.

R134a Disposal