hi am working on 1977 280 se and we have replaced the ac compressor it is running fine. the high pressure side is hot and the low is cold as is proper. but inside the car the fan will only blow low speed and the air is very hot. it seems that the hot water valve is on and the (air valve or vane that directs the air from the heater core or ac evaperator ) isnt changing. the defroster blows lots of air when the def is turned on. there are about 20 vac lines going to what i think it the water control valve.the hot water is on. can someone point me in the right direction? thank you .....digger