This weekend I just completed the conversion of my 3.0 1990 Aerostar from R12 to 134a. Changed reciever/dryer and both o-tubes. The issue is how much 134a to put back in. The label on the blower housing says 4.0LB for rear air Aerostars and mine has rear air. So here goes.

If I only rechange 134a to 85% of full R12 capisity see if my math is right?

(1.) 4.0lb's of R12 is 16oz times 4 = 64oz of R12 at 85% for 134a is 54.4 oz of 134a.

(2.) Four cans of 134a are 12oz each so if I put in 4 cans of 134a and the ester oil charge which has 3oz of 134a and that comes to 48oz + 3oz for 51oz of 134a

Does that sound right?

Andy

 

yep....i'd shoot for 80%, but 85% is good too

The Aerostar has a SMALL condenser.
An Auxillary electric condenser fan would be helpfull.