i have an 88 740 turbo. the directional control for the A/C - heating system does not function hence i cannot get the air to come out of the dash board vents. the blower works fine and the temp control works fine - problem is directing air flow. when set on defrost or foot well setting, some air comes out but not much with blower on hi. is there a relay i need to replace? is there soemthing that needs to be lubricated? any help greatly appreciated. with 90+ temps, it is getting a little hot in here!