I have seen some retrofit fittings for r-12 cars to allow 134a hose connections. When you screw those new fittings on do you have to remove the r-12 Schrader valves or does the new fitting depress the r-12 Schrader valve?
If your new adapter has a valve in it, you should remove the R-12 valve. You do not need two valves. But…..read the instructions! Bones
The ones I have used screw on and operate the original valve, no need to remove them. This way you can remove the 134 adaptors to use on another system.
When I did mine 15 years ago I first drained the r12. Then i simply installed them over the r12 valves without removing schrader valves. I vacuumed the system for about 30 minutes and recharged to about 90% of the r12 capacity to compensate for the higher pressures. The a/c blew just as cold feeling the r12, no other components or oil was changed. I drove the vehicle for 12 years daily and never had any failures
Exactly! An old time A/C man, still in business here, told me they started "converting" the "right " way . They learned, over time, to do just as you did. Ben
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