Front defogger/defroster questions

Gray05

New Member
Oct 19, 2009
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Northwest
So I recently bought a 1990 Supra. Its in so so condition and Ive been doing research on its problems. One of my current annoyances is the front defogger.

I havent been able to find much info on it specificly. Im pretty sure that the climate control unit is atleast partially dead. When I press the button for defog, it lights up until I let go, then it flips back to the default. Is that caused by the CC or is it because the blend door servos arent working?