On this year vehicle the flapper should be vacuum controlled. You may want to look at the vacuum lines going to and from the vacuum canister in the engine compartment. If it will change from floor to dash but not defrost then you may have a failed vacuum line or diaphragm in the dash from the selector.
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On this year vehicle the flapper should be vacuum controlled. You may want to look at the vacuum lines going to and from the vacuum canister in the engine compartment. If it will change from floor to dash but not defrost then you may have a failed vacuum line or diaphragm in the dash from the selector.