Originally Posted by konstan

I have, however, never bought any R12 because by then it was already so expensive that it wasn't worth it. Checking into the price of the new receiver/dryer and even a new compressor, it made it obvious that converting to R134a is the way to go.

Originally Posted by konstan

I haven't read the whole thread, but I saw the title and I felt that I needed to chime in Sorry if I am stating the obvious here.

I filled out the application and the test several years back and I am R-12 certified.

I have, however, never bought any R12 because by then it was already so expensive that it wasn't worth it. Checking into the price of the new receiver/dryer and even a new compressor, it made it obvious that converting to R134a is the way to go.

I have successfully converted two of my vehicles to R134a: a 1982 Toyota pickup and a 1993 Ford Explorer. There is nothing to it. On the Explorer, I had to replace the expansion valve (a $3 plastic piece). On both of them, I had to replace all the o-rings. Basically you unscrew everything and replace all the black o-rings with the green ones.

You will need (buy or borrow) a cheap Harbor Freight manifold, some cans of R134a and a can or two of PAG oil. Buy the oil and the refrigerant at Walmart. To evacuate the system (pump out all the air) you borrow a vacuum pump at O'Reilly or AutoZone.

The whole job takes a couple of hours. Be sure to replace the receiver/dryer, and if the A/C compressor is suspect, they are cheap - the Mercedes A/C compressors for the U.S. imports were the cheap GM ones.

Finally, about the "R12" substitites. There aren't any. There are some that have a mix of R134 and propane gas (yes, propane), and that's downright dangerous.

Convert to R134a.