Buy OEM 1991 Mazda Part # KD4761A1Z (KD47-61-A1Z). HVAC Mode Door. W/AUTO AC. W/AUTO TEMP CONTROL, Japan built. HVAC Blend Door - Repair or Replace In some cases, albeit relatively rare

Damper, Heater Unit. HVAC Mode Door.
HVAC Mode Door. Included with: AC & Heater assembly.

HVAC Blend DoorHVAC Mode Door

Fits 3, CX-5

W/AUTO AC. W/AUTO TEMP CONTROL, Japan built.
HVAC Blend Door - Repair or Replace
In some cases, albeit relatively rare ones, a blend door in your HVAC system can break, causing air to come out of the wrong vents or at the wrong temperature, or not to come out at all. Properly diagnosing such a problem in your 1991 Mazda is best left to technicians with factory training and expertise.