AC charge amount for 92 740 turbo?

I got the leak on the condenser fixed and it is ready to recharge as
soon as engine repair is complete. I have Haynes and CHilton manuals
but neither gives info on specific amounts for ac recharge, or normal
operating pressures. I looked all over for a sticker with this info
(on original r-12 charge) but didn't find one. I got a case of
DuraCool to try in it. I COULD just charge blindly until it is
cooling, but would rather know what system pressures are supposed to
be with the (equivalent) DuraCool charge (you use a lot less by
weight), so I know when to stop. This refrigerant is supposed to run
with a lower high side pressure.

 

Our '85 765T was dealer converted to R-134a, and I'm sure it has stickers.
I'll post the weight when my son-in-law returns with it (about 3 more hours)
but it would be good to find out from the more experienced people here
whether the charge would be the same, or even close.

I suspect the condensor fan will have to be on whenever the A/C is running.
It probably is already, but be sure to check.

Mike

 

3 cans of R-134a is very close to the specified charge. Keep in mind you
have to replace the reciever/dryer any time the system has been opened,
then you need to pump it down with a vacuum pump before charging. When I
do it, I put it on the vac for about an hour to get all the moisture and
other non-condensibles I can out of the system.

 

The sticker under my hood says a 92 740 gets .95 Kg (2.1 lbs) of R-134a

Mike