hmmm. red plug would be the high pressure cut off switch. unplugging that kills power to the clutch...leave it plugged in.
cool air in center vent only points to issue with doors in the hvac system not working properly.
Ac pressure should be around 190-200 with R12 on the high side and around 15-20 on the low side with a proper charge. If pressure is bouncing around it could mean the compressor is bad.
With the ac on the low side should drop in pressure (to no lower than 10psi) and the hight side should rise(not go higher than about 210). Anything else means component problems.
cool air in center vent only points to issue with doors in the hvac system not working properly.
Ac pressure should be around 190-200 with R12 on the high side and around 15-20 on the low side with a proper charge. If pressure is bouncing around it could mean the compressor is bad.
With the ac on the low side should drop in pressure (to no lower than 10psi) and the hight side should rise(not go higher than about 210). Anything else means component problems.