quote:
Originally posted by Gary Allan:
I just did the conversion. Works flawlessly. My cost - $36 IIRC. Local AC service, with the only added service being having it vac'd and the O rings changed - $150-200.
Ok that makes sense. I was under the impression that you just dumped the R-134a on top of the R-12 which is a major
We call that a retrofit. There's a little more that should be done though.
First you should always replace the Reciever drier/Accumulator. The R-12 dessicant won't work with R-134a.
Depending on the car you should change the orface tube to one thats .010 smaller or put in a VOV tube which compensates automatically.
If the car has a valve instead it should work ok.
Add the proper Pag oil and leave the old mineral oil in the system to act as a barrier in the hoses. Add 4oz of Pag oil for every lb of R-134a.
To be legal you need to install a high pressure shut off switch in the high side line. R-12 does not normally build up high pressures but R-134A will in a matter of seconds if there is no airflow across the condensor.
This switch Should turn the compressor off @ 400psi.
Some cars work fine others do not. Retrofit a 1985 K5 Blazer to R-134a and the customer won't be happy. You will have to sell them a more efficient condensor as the old condensor simply won't work well on a very hot day.
Make sure that their fan clutch is working! Install a 195 Stat and the fan clutch should pull more air at low speeds which will make the A/C work better.
Retrofit a 1985 Ford pickup and it will freeze you out! Ford condensors are much more efficient than GM ones.
Chryslers usually work ok as do most Japanese cars except for Mazda's. IMHO It's generally best to keep a Mazda with R-12 if it originally came with R-12.