m Ransley wrote:
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 we

1. Vacuum the system removing all R12 and check for leaks.
1a. Turn A/C on high setting.
2. Insert one can of R134A oil charge.
3. Bring system up to normal level using R134A.
3a. Compressor should start turning.
4. 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