I have a 84 300d with about 300k on it. The compressor is new and I recharged the system per the direction on dieselgiant.com

I pulled a vacuum to 100 microns before I recharged the system.

The drivers side vent it blowing 70 on an 90 degree day.

When I press the 2 middle buttons on the ACC, they both blow on the windshield. I can not get air to blow out of the 2 center vents no matter what button I press or where the dial is set.

I checked the electrical voltage at the mono-valve when the car was started with the ac on, ac off and heat on and it showed around 12v regardless of what I selected on the ACC.

The clutch on the compressor is engaged when any ACC is pressed except the econo which seems to be correct.

I don't know if the evaporator is fighting the coolant going through the heater core or if I'm low on r12.

Should the mono-valve be open for heat and closed for AC?

Is there a way to test the mono-valve so I can eliminate it from the possible cause?

I don't have an infrared thermometer but I was thinking I could take the temp at the expansion valve and that could help me diagnose the problem. I am going to stick a regular cheapo thermometer on the expansion valve and see what reading I get.

Any other ideas or suggestions?

Thx

pete