heating issue with temp reg flap

hi to everyone im new to this forum but hoping someone can shed some light on my heating issue.

heater temp flap is no operating - ive done some checks and everything seems ok with the temp reg flap servo motor and climate control unit.

so far i have taken motor off car checked that the temp reg flap servo motor inside the case is working with a 6v battery charger as it is a 7v motor

tested temp reg flap servo motor as a unit and motor runs fine even if you try to stop it it dont fail under load

checked resistance on potentiometer and all reads good at 4.7kohm and reduces or decreases when testing from centre pin to outside pins of potentiometer

put it all back together and dont work in the car

ive changed the climate control unit completely with no joy and changing the ambient temp sensor at the fresh air blower as this is showing as static open but has been before the motor didnt work so cant see that this is going to make any difference 

has anyone got a wiring diagram of the heating system and /or what could also be in control of this motor  ???

had car dash in  pieces for last 2 weeks driving round with a dismantled loose dash is not easy

thanks in advance for any help