On NA/NB Miatas the temperature blend, the mode (where the air comes out), and recirculation are cable-operated, so "no heat," "stuck on defrost," or "won't switch to recirc" are usually a disconnected or misadjusted cable or a crumbled foam flap, not an electronic actuator. These cars do not have the blend-door motors that later cars use.
Match the symptom to the cable it drives
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