Expert: Candido Figueroa - 7/20/2010

Question
Retrofitting a '93 Ford F150 to R134a. R12 is too hard to obtain. The old compressor had a bit of a rattle and when drained had almost no oil. Replaced the compressor and the accumulator. All new seals, R134 fittings etc.. Haynes manual reads 7 ozs. plus 4 addditional for this particular truck. Triple evacuated and broke first two vacuums with R22. Vacuum held for 1 1/2 days with no change and then I added R134 with a big shop fan right in front of the radiator. Engine RPM @1500. Original system was 44 ozs.R12. Added 36 ozs. R134a (80%)Pressures way to high on suction it's 50+ and high side is 300+. Spraying water on radiator brings pressure down but goes back up after a bit. I reclaimed a bit of the R134a to obtain 30+ suction and 250 Hi. Outlet temp is only low 60's. Wondering if the extra 4 ounces of oil have loaded up in the evaporator.  Could this be causing high side restriction? Thanks

Answer
Hi Jack

Yes it can cause a problem.  I would add some refrigerant and let the suction go to about 40psi and the high should stay at about 275psi.  On some model vehicles you could only add 75% so maybe you pulled out too much refrigerant.  Add some refrigerant before you go and flush the entire system which will cause more harm if any of the flushing fluid stays inside the system.