We have a 1990 Buick Regal 3.8L... no heat... blower is fine on all settings. New water pump, new thermostat, all hoses get warm (no clogged heater core) When sliding switch from cold to warm I hear no noise, ie blend door actuator opening? All other vacuum issues are good... heat, vent, defroster etc. I believe the blend door is operated electronically? so Im not sure if that is relevant. I can buy a blend door actuator for 20.00 or a heater/AC controller used online for 27.00... I cannot for the life of me locate the blend door actuator! I have taken apart most of the dash...does anyone have a pdf of the dash internal? Am I missing anything? So much easier to pop in a heat/ac controller. THANKS so much in advance. I live in Illinois. Baby its cold outside (meant no offence)

I assume this is single zone, not dual zone?

If single, I think the actuator is on the passenger side...pull the hush panel on the passenger side and also the glove box.....should see a wire harness going to a temp actuator......disconnect it, and then remove the 5.5mm hex heads holding it in place.....now grab the temp door to see if it moves....with the engine at normal temp and blower on, manually move the door to see if you get heat.....If you do, it'* the actuator or head.....just three wires to actuator...power(pink), ground(black), and control(light blue).......check for power, ground, and a variable voltage on the control line when you change the temp setting......if this checks out, it'* the actuator(gear usually goes on these).....

Thanks so much! It was your wire colors that led me to the holy grail. Followed those to the unit... removed the three wire plug and checked voltage - supplied voltage is good, 2.0 cold 12 hot... removed the actuator and manually turned blend door gear with warm car and there is my heat!

Thanks again! BTW the only required removal for access is the hush panel and then I dropped the relay panel? out of the way to gain access to the 2 screws.