Running R12 In A R134 System

[philipswanson]

I am rebuilding the air conditioning system in my motorhome. It is a 1995 so it came with R134 from the factory. I am thinking about going backwards and converting it to an R12 system to make it run cooler. I have plenty of R12 so that's not a consideration. Question is: Is a system designed for R134 capable of running R12 with no ill effects? Naturally it would be totally purged and run with Esther oil.

[Cusser]

I'm probably wrong, but I thought that R-12 was only legal in systems originally built for R-12.

I still have an R-12 truck, but will confess that my 1998 and 2004 Frontiers and 2005 Yukon with factory R134a are really cold, and I'm in Phoenix AZ.

[philipswanson]

Not illegal. But can it be done mechanically? That's the question.

[Cusser]

Not illegal. But can it be done mechanically? That's the question.

With the equipment I already have at my home, I could technically fill an R134a system with R-12, and vice-versa. Without changing/converting either of the service valves.

[philipswanson]

What about the expansion valve? Doesn't that need to be changed to run R12? Some valves specify R134.

[Dougflas]

What about the expansion valve? Doesn't that need to be changed to run R12? Some valves specify R134.

R12 and R134 are so close I would not change it