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Using R134 to test in an R-12 system

Posted: Fri Jul 14, 2017 10:12 am
by robmaxfli
I've got all new AC components in my 1992 Buick - nothing reused. I hooked everything back together and pulled a vacuum but it will not hold overnight. I have already added R12 Mineral oil and UV Dye into the system. I have R12 that I want to recharge with eventually.

I then used plain shop air to pressurize the system up to 80 psi - then I used soapy water on all of the connections to see if they would bubble up....I can't find a leak.. :x

Can I use R134 to leak test with even though I have Mineral oil in the system? as long as I don't turn on the compressor?

Re: Using R134 to test in an R-12 system

Posted: Fri Jul 14, 2017 11:25 am
by Cusser
robmaxfli wrote:I then used plain shop air to pressurize the system up to 80 psi - then I used soapy water on all of the connections to see if they would bubble up....I can't find a leak.. :x
Not so good - most shop air contains some moisture, not good for the drier pellets !!!

robmaxfli wrote:Can I use R134 to leak test with even though I have Mineral oil in the system? as long as I don't turn on the compressor?
Yes. The advantage of R134a over dry nitrogen is that R134a responds with electronic detectors.

Re: Using R134 to test in an R-12 system

Posted: Fri Jul 14, 2017 12:08 pm
by robmaxfli
ok - If I add R134a will that distribute the UV dye that I added (without turning on the compressor)?
thanks

Re: Using R134 to test in an R-12 system

Posted: Sat Jul 15, 2017 6:01 am
by Cusser
robmaxfli wrote:ok - If I add R134a will that distribute the UV dye that I added (without turning on the compressor)?
thanks
Doubtful.