I have a 71 skylark. I have the vacuum hose chart that shows blue vacuum line goes to the defroster actuator and the pink line goes to the A/C and heater mode actuator. My question is what actuator is the defroster . my heater box has an actuator on the very end of the box and one in the center of the box. Which is the blue and which is the pink line.? Thanks Michael
Pull a slight vacuum on each & see what it operates inside the box. Chassis Manual might get you a pic of the ducting incorporated in the system & mounted under the dash.