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Old 07-21-2000, 08:52 AM
Posts: n/a
This was a JakeLeg job of conversion, but I'm sure you already know that.

R12 and R134 are so incompatible that this caused the change in fittings and guage sets. I've been told to never get the two near each other.

First of all, the quantity should not be too far off, but a little low. According to Benzmac, and I have seen this work out pretty well a few times in practice, you should charge with 75 to 80% of the specified volume when changing to 134. In this system, 2.2 pounds would be about 35 ounces, 75% would, of course, be about 26 or 27 ounces. I believe that as a bare minimum, this system should be emptied, and the oil changed to Ester. It would be better to break connections and flush aggressively as you put it. If you do this, change to the green O-rings, put in the Ester and pump it down. Whenever you have the time to do so, it's very good if you can pump down for 24 hours. In any automotive A/C, R12 or R134, any moisture in the system combines with the refrigerant to produce an acid which can eat up evaporators and other components from the inside out. R134 is much more prone to developing this acid when combined with moisture left in the system. This is why I always try to pump down a system which has been broken apart, for 24 hours where practical.

Good luck,

Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

[This message has been edited by LarryBible (edited 07-21-2000).]
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