Hmmmm ..... have you tested your recirculation vacuum controller/system?

As I understand it, the air goes through the heater core whether or not hot water is supplied to it (thus the function of the temp control).

I am wondering whether somehow your system also goes to closing off the fresh air portion of the system.

Try this (yes I know right now it is crazy with the low temps) turn on the AC, try to get it running and outputting cold air. Make the recirculation work. Does the light come on?

Do you get the headache feeling right away?

Haasman

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