"R12-replacement" - Page 3 - PeachParts Mercedes-Benz Forum

leathermang · #31 04-06-2010, 09:32 PM

Quote:

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.

"I have, however, never bought any R12 because by then it was already so expensive that it wasn't worth it." ----Konstan

To be viable in trying to help others you need to check to see if the facts have changed since you had your experience. For a while ( ten years ago for instance ) R12 was very expensive... particularly if quoted by a local repair shop .. but for many years now the price has been very reasonable and WELL WORTH IT...
If you had just read the posts in the archives concerning the price you would know this.
So to give a blanket ' Convert to R134 ' recommendation is sketchy...
It is good that you know that if one is going to move from R12 that R134a is the correct choice at this time. It can also make a difference where the person needing AC help lives... Advice for Texas is different from Maine...

DeliveryValve · #32 04-06-2010, 09:48 PM

Quote:

Originally Posted by Rudolf_Diesel

A buddy of mine replaced my R12 with R409a it is a direct replacement for R12 and only requires removing the R12 - no other changes are neccessary.

What I've read about R409a is that it is not recommended for automotive applications (mvac). Only stationary systems (hvac) likes vending machines, refrigerators, humidifiers and others. Did they change the recommendation?

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