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Previous owner used 134a, Go back to R-12 help!

kyle22 on Mon May 05, 2008 2:59 AM User is offline

Year: 1985
Make: Mercedes
Model: 300D (W123)
Engine Size: 3.0L
Refrigerant Type: R-12 (original)
Country of Origin: United States

Please help... I bought a Merc a few months ago, and the A/C comp. (R4, unfortunately) would kick on under most conditions, but it didn't get that cold... The previous owner had the 134a fittings on the system, so I put some 134a in, plus a shot of ester POE oil.

As the weather gets warmer, I can tell that this is no good at all.... I have plenty of new Freon-12 (Yeah, the real stuff, from DuPont, NOT Freeze-12 or other BS....) and a 4Oz can of Interdynamics oil charge.

My question is.... How can I know if the previous owner put the evil PAG oil in or not.... I am guilty of putting some ester oil in, but I understand this works with F-12.

What about a mix of ester and mineral oil, will that work? ...... What if there is some PAG in there?...... How can I flush this?

I have a new receiver-dryer on order, should be here in the next day or 2. I know that's a definate thing to have.

The R4 comp. is on the bottom of the engine, and difficult to get at, must I remove it completely, or is there some way I can flush all the bad oil out?

What if it's ester oil that's in there, how can I tell what I have? Will it hurt to mix w/ mineral oil and Freon-12? How much trouble will I have with PAG turning to sludge? (if present)

Please help.


HECAT on Mon May 05, 2008 5:23 PM User is offline

Since you just purchased the car, you added oil, and by your own questions; there is no way of knowing what concoction is already in there. Check out the procedure page for info on flushing and oil flushing the compressor. Clean it to bare metal (dry), flush the compressor with oil (no solvents), vacuum, and fill with the correct amount of mineral oil and R-12.


HECAT: You support the Forum when you consider for your a/c parts.


kyle22 on Tue May 06, 2008 12:19 AM User is offline


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