Sorry, I cannot answer your question but I have a similar problem The center vents (ie top of dash for defrosting windshield) stay open. I thought it might be a bad vacuum switchover valve and cannot find this valve. Is this valve what you are calling actuator? Someone told me his ('85SD)was located beneath the side carpet, passenger side of center console and I would not need to remove the glove compartment. Have not looked yet but do you think this valve is the one you located inside - which means I must remove the glove compartment?