[v2rocket_aka944]

This was bugging me so I had someone take a photo of the sticker on my car (in another city currently...)

Early 944 called for 40.6 oz of R-12, so Porsche's recommendation of 36oz of R134 makes 89%.


I think the 33 number is for late models, then.

Originally Posted by v2rocket_aka944

For reference, here is TSB..
http://www.pcarworkshop.com/images/e/eb/Retrofitting_R134a_A-C_1995_680195.pdf

Kuehl, I find this interesting though, I've not seen that TSB before.
However, the sticker on the fender of my early 1985 944 says something like 33oz R-12 charge, so fitting 36oz of R134 would be 10% extra??? That can't be right.

Originally Posted by kuehl

I believe the factory R12 sticker on the 85/2 says "33.5" oz R12.
The rule(s) of thumb for R134a conversions can be found to say 80%, 85%, or 90%.
We generally use 85% when the amount is unknown, however adjust the final charge based on P&T (pressures and temperatures).

Hence, the factory TSB states 30 oz R134a for a 33.5 oz R12 system which means they suggested 90%. But once again, we prefer to adjust the final charge based on P&T.

Maybe your 85 has the smaller 10P15E compressor and later condenser and evap,
OR they goofed!

Must be the .01% rule