AC conversion to R134 question

[Alex Hayley]

I am converting from R12 to R134. I am replacing all of the o-rings right now and figure now is a good time to be getting rid of the original AC oil. What have you guys done to get rid of the oil? Am I going about this the correct way? Kind of a vague question....

[Zkast]

If your dead set on converting it to 134a there are several things you need to do.. although I will say this, as long as r12 is still around I would stay with it. R134-A will do *OK* in your truck but lets face it, these cabs arent exactly air tight hehe and with that you will loose 20% of your cooling capacity. On the best day a 134a system can only reduce inside cab temps by 30 degree's off ambiant temp. It's up to the recirculate system to keep the cooled cab air inside. ok ok I'll step off the soapbox lol.

134 conversion: Using either de-natured alcohol or an A/C Flush solution (costs about 40$ per gallon) You will need to get every ounce of oil out of that system. Reason is, The oil will not mix or blend with 134a freon. It floats at the top of the evaporator and reduces heat exchange. NOTE: Whatever you do, DO NOT use brake clean. It dries out any rubber it comes into contact with and will induce leaks.

You will need to change over to the orfice tube system also...

Next is the condensor, R-12 condensors are thin and carry a smaller amount of freon (gas and liquid form) R134 systems use a condensor that is nearly twice as thick. This is why most conversions dont have great results, most people choose to use the old condensor.

When charging your system, it is very easy to overcharge with 134a. The system will take aprox 5-10% less freon with 134a.

I know R-12 is very expensive but its still availible. At our shop we decided to stay with R-12 as long as its still out there... and discourage anyone from converting. It's just not worth it.