GMC Repair: A/C Cold air Stopped 2002 Grand Am GT, request signal, pressure sensors

Question
First let me say THANKS for the time you spend helping people. Last week I bought a 2002 Grand Am GT. After driving it for 2 hours, the ice cold air stopped being cold! Blower blows fine. Took to A/C mechanic and was told they found NO R134 in the system. They filled (& added dye) but can't get the electronics in the system to "energize" the system to move the dye anywhere. Clutch not moving, etc. They are checking with scanner at the engine computer, but no request signal is coming from (either) the HVAC control (box) or from the BCM. Recommendation is to "try" replacing one, and if not, then replace the other (& about $300/each) Can't those two components be "tested" before replacing, and do you have any other ideas. (All A/C fuses/minirelays, etc seem to be fine, not blown) Thanks

Answer
Hi
First THANK you for your question and for allowing me to try to help.
The request MUST come from the HVAC control module first.
If the request signal is always "disabled", I would REALLY be looking at BOTH the HVAC control button OR the request signal wire from the HVAC controller to the BCM.(Light green from C2 terminal B (HVACcontroller) to C3 terminal B7 (on BCM).
It should vary in ground in BCM when "enabled"
My Real main problem here is it was working fine?
Did this happen suddenly? I really cannot understand an electrical problem causing the freon charge to go low.
Have them DOUBLE check all the pressure sensors for correct readings on the scanner. (should match closely to their gages hooked up)
I Hope this all helps.
Please follow back post if needed.
Good Luck
Pawl