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Yes, you are showing an undercharge. If adding 12 ounces did not push the high side above 190, you were really low, and still are. The reason adding the refrigerant didn't effect your vent temps is because by the time you added the gas, the evaporator was frozen. The anti-frost switch should have shut down the compressor when the evaporator froze. Mine isn't working either and I have not had a chance to figure out why.
Is the vent temp of 80 with the doors open or closed? Not that it matters if the evaporator is frozen.
As a general rule, I would suggest that you charge to a high side pressure that is 2.8 times the outside (ambient) temperature. In your case, that would have been in the range of 230-245. The expansion valve may not work right in the case of a major undercharge, so that could be part of your problem. You will have to get the gas in before the valve freezes up. I would have expected the low side to first settle around 30 and then pull down ultimately to 15-19.
The very low low side pressure indicates that the expansion valve is fairly closed, and is then freezing that way. For instance, the initial low side of 16 was already a little low. We could be talking about an evaporator temperature of under 10F. If the expansion valve started to freeze that would cut off more flow, causing a serious restriction. With the compressor pumping away at that blockage, you would expect the high side to start to climb. The fact that it didn't, indicates a continuing undercharge to me. Also, once it was frozen, you were not going to get anything noteable happening until the whole thing had thawed out.
Didn't the shop originally tell you they had put in 48oz of r134a? Where is all this gas going? Is the dye you see around the high side port on the threads of the r12 shrader valve, or on the compressor body? The thing is that every time you take the high side coupler off, some refrigerant is going to shoot out in that general area. That makes diagnosing a leak there challenging. Who put in the dye? Do you need a black light to see it?
I think we need a better description of the work you did. In particular, what did you use for oil? Did you soak the o-rings in oil before installing them? Did you flush? If so, with what? Did you remove the valve cores from the r12 ports on the compressor before you installed the r134a fittings?
Also, if you haven't already, you might want to stick your hand in and see if there's an air leak around the blower motor, and check to make sure the control arm for the air mixture flap is still attached and moving.
What I would do is to hook up the gauges after the car has been sitting for a while and see what the pressures look like at 1500. If they are still low, add another half a can with the engine at idle speed. Idle speed should keep the low side high enough that the evaporator doesn't freeze. Then bump it up to 1500rpms and see what happens. If adding more gas doesn't cause the pressures to climb, you either have a major hissing leak or the expansion valve is stuck shut. Or both. The good news is that your leak could well be a dry o-ring, and I just bought an expansion valve from eeuroparts for $16.
posted by 24.50.57...
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