Calculation

If you want to change from R12 to R134A how do you calculate or estimate how much gas you will need?

The book says 975 g but that is R12 and as far as I can remember you should only fill up to 650g or so with R134a.

Am I right or wrong?

//B//

 

Don't do it.

R134 is less efficient. It requires larger evaporator and condensor coils to achieve what R12 did.

So that tells you you will lose efficiency to backward convert the system.

Gas volume would be about the same as R12.

Big mistake. Don't do it!

 

Can´t get hold of the R12 here anymore.

Like I wrote in another thread I have to go to Poland to get it done in that case and still sitting like a duck if they catch me.

Got no choice as it looks like.

//B//

 

Hi
I've had a same problem here in Moscow for my 911,
Specialists said should not do it due to gas may destroy (corrosion ) old system. I dont know if it is valid only for 911 , but double check with specialists.
I had to change complete system

good luck
A

 

I just go off the head pressures, about 15-20 for the low and about 230-250 for the high

Don't forget to add a bit of oil also