A/C COnversion Issues
Thread Starter
Cruising
Joined: Jan 2006
Posts: 13
Likes: 0
A/C COnversion Issues
1972 350 Converted to 134A. Flushed system, all new hoses, new Rec Drier, New compressor, (used ester 100), new expansion value. Held good vac before recharge. Put in apprx 45 oz 134A. getting major frost on lower end of POA value. No cold. Any suggestions?
Melting Slicks
Joined: May 2002
Posts: 2,716
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
Originally Posted by 72OrangeCoupe
1972 350 Converted to 134A. Flushed system, all new hoses, new Rec Drier, New compressor, (used ester 100), new expansion value. Held good vac before recharge. Put in apprx 45 oz 134A. getting major frost on lower end of POA value. No cold. Any suggestions?
Neal
Instructor
Joined: Jan 2003
Posts: 237
Likes: 0
From: TAMPA FL
You may have to much r134 I just did this conversion and used about 30-32 oz. of r134. Find out how much r12 is called for and reduce this by 20%. This is where I started then I added a couple oz more to bring the presure up to where it needed to be.
Dennis
Dennis
Cruising
Joined: Jun 2006
Posts: 10
Likes: 0
From: Lampasas Texas
Sounds like you replaced everything except the evaporator and that may be exactly what is wrong. If the evap is dirty to the extent that air will not pass through it then it will freeze your sytem up. Since I am a new Corvette owner I cannot tell you the easiest way to check the evap, you will want to check the side of the evaporator where the air is entering (engine compartment side). In addition, if your evap is blocked there is no way to get accurate readings on your low side manifold gauges and you can very easily overcharge the system using liquid (can upside down) to charge. Dennis is right on the conversion, r134 generally is an 80% charge of R12. One more thing, when you drew a vacuum did you hook up both high and low sides? Good luck
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
Pull the fan blower resistor module out of the evap. housing. This will let you look into the inlet side of the air box to inspect for trash and to let you inspect the heater door making sure it is completely closed. FYI...On a 'Vette we just finished a conversion on, we were scratching our heads. The gauges were good #'s, and the evap. was very cold, with 60 degree outlet temp. The heater door was cracked open about 3/8 inch! Closing the door brought the center duct temp. down to 42 degrees in a 98 degree shop.
