I have a 1970 BB Coupe that I am looking to upgrade the AC to R134A. Who out there has done this?

So, did you keep the original sytle POA valve in the system or go to the replacement valve with the switch that cycles the compressor ON/OFF.

I am planning to keep the R6 original compressor and just reseal it and change the oil in the system to a PAG type synthetic. Looking to flush the lines, condenser and evaporator as well. Will replace the original rubber compressor lines with new unites.

The search function did not find any threads that dealt with this issue. Any help/experience with this issue is appreciated.

Bob

 

The search function on this forum just doesn't work well for anyone. Do a Google search. Just put in, "C3 Corvette ................"
​​​​​It will bring up many answers that bring you right back here.
And yes, lots and lots of us have upgraded our air-con systems.
Keeping your original compressor and condenser can be done as you wish to do. But certainly not the best way.

 

I've done this on my '71. I started with a completely stock system and just charged it with R134a and the correct oil. It did not work well with vent temps in the high 50's. I never had it working with R12 but the shop manual says normal vent temp on a warm day is 52F vs 38F for the same year Chevelle so the Corvette system is marginal it seems.

Next I replaced the POA valve with one that is adjustable. This was many years ago, don't know if they still make them. It's not a cycling switch, the compressor still runs all the time. The adjustment is for the pressure it feeds the compressor. This helped a lot and got the vent temps into the high 40's. Still had two problems though: It took a long time for it to cool off and second problem was that after driving for an extended time (hour or more) the evaporator would freeze.

So to fix that I swapped the condenser out for a modern parallel flow unit and I installed a freeze cut-off switch that was OEM on late 70's GM pickups. It has a copper tube you stick into the evap box and then you connect the switch inline with the compressor clutch wire.

Finally I replaced the A6 compressor with a Sanden for the weight savings and much better spark plug access.

End result works well. Vent temps in the mid to low 40s. I rarely have to turn it on full blast, only when it's been sitting outdoors in the sun on a 100F day. Otherwise setting it to "Normal" with fan speed 2 is plenty.