I bought a restored ,72 Cutlass Supreme which has the A/C changed to R-134a. I've had it about three years and the A/C needs a shot of R-134a.


On the sticker that is on the evaporator, it says that it has been changed to R-134a, but then it has 8.5 lbs. listed as well.


Does anyone know if that the correct spec as it seems low to me. If it's incorrect, how many pounds should I bring it up to for a refill?

 

I think most A Body Oldsmobiles were charged with 4# of R12, 8.5 sounds like a lot of R134..

 

8.5 is not right, way too much. You really need to throw gauges on it to see what you need. Too much is just as bad as low.

 

When converting to R134, if I recall, you generally charge with about 80% of the amount of R12 specified.

You also need to change the condenser and the receiver/dryer and recalibrate the POA valve.

If it says there's that much R134 in it, then everything else needs to be checked.

- Eric

 

What MDchanic said. Recalibrating the POA is often ignored, and it doesn't work well with 134a. And a real POA calibrated is much better than the POA update, or the POA bypass that most places sell. I had my POA recalibrated by Classic Auto Air and also bought a Cross Flow Condenser, which is the weak link in using 134a. Most people complain that the 134a doesn't cool as well, especially when sitting in traffic or at a light. With new o-rings, a cross flow condenser and a recalibrated POA I get outlet air consistently in the lower 30s, in south Florida.


The cross flow is what goes in front of the radiator and cools the refrigerant. The stock condenser can't cool the 134a effectively. That is why the outlet air temps are not cool enough using the 134a in an otherwise unchanged stock set up. The cross flow is the same size and shape and mounts identically tio the original unit.