I have just taken out of storage and cannot get the blower to switch from floor to dash vent to defrost. Where to I start?

If it is blowing out of the floor vent, then take off that lower directional piece and using a mirror and flashlight, look up the opening and see if there is something stuck in there. If not you should be able to reach the air doorright in there and manually activate the door. It does have a spring on it so it should return. If it does not move easily then this may have seized inside there. If it does move easily then the vacuum servo that works that may be stuck or there may be a vacuum leak in the line going from the switch to this servo. Do you hear any hissing from under the dash while the engine is idling? If so look for vacuum l;eaks. Otherwise you may have to change out this servo.

You should look at a manual to review how the system works to make sure you are replacing the involved servo.

Check the vac line from the intake manifold to the a/c vac reservoir (ball, or similar). Typically, the "default mode" when no vac gets to the a/c instrument panel control, or the vacuum director mechanism in there leaks or is broken, is "floor and defrost" air output--even on a/c. Might also be a vac actuator, as JohnD mentions. This even works for the later model vehicles before they went to electric mode door actuation.

Just some thoughts and observations,
NTX5467

Thanks for the ideas. I have ordered a manual for the car but didn't have the patience to wait for it.

I'll be under the dash this weekend.