I drive a 1989 300sel

OK i need some help this is driving me crazy, the climate control seems to have a mind of its own, it seems unwilling to change what its doing. IE Ive had air conditioning running now for 3 weeks, before that i could only get the heater running.

so far i have not tried that much all i have done its pulled the climate control module out and done a blanket resoilder of the hole board (part number 1268300885)

It used to be that you could get the climate control to change by switching the climate control off when the motor was running. then turning off the motor, changing all the setting then starting the motor again but that no longer seems to help

sometimes when i start the car it seems to think about putting the heater on (you know how it seems to like blowing air at your feet when its heating and blowing air at your face when its cooling.....) but then it stops for a second and then i think it starts the compressor, i can hear the load on the motor

i just all so want to say when the heater is running its nice and hot and when the air con is running its icy. Its just getting them to work when I want them to and thanks for any help