auto ac, r12 - r134a

[Yeva Kravchenko]

A friend has been filling R12 systems on cars with R134a and says

> there is no need to evacuate out R12, he has done it for years on many > cars. Is he lucky to not of had his friends cars damaged or can I just > put in R134a in my R12 system without evacuating out R12. >

This procedure was listed on Interdymanics web site after R12 was discontinued. They make the freon. For conversion to R134A their instructions were:

1. Vacuum the system removing all R12 and check for leaks.

1a. Turn A/C on high setting.

1. Insert one can of R134A oil charge.
2. Bring system up to normal level using R134A.

3a. Compressor should start turning.

1. Check for leaks.

I've used this system for many years with no problems. Actually I still use my R12 gages on the R134A can. At your hardware store in the gas fittings you will find an adapter that fits on the R134A can piercer to the R12 hose. As the pressure on the low side tends to get near the normal level I monitor the temperature. When it gets to the normal cool setting, I quit adding. If you might not be the next person to add more freon make sure you indicate with a label somewhere under the hood that it's now R134a since you can't go backward to R12. If anyone has any problems with this method, look on Interdymanics Web site.

Best regards, Yeva