Hello, ac may be the cause.ok.

Headache is seen with the use of AC under 3 conditions: - Cold, dry air dehydrates you: The AC reduces the humidity in the air which can lead to dehydration which can cause headaches, in which case you can use a humidifier to make the air moist, drink plenty of fluids. - The cold temperature stimulates the trigeminal nerve, causing your brain’s blood vessels to constrict and thus create a headache. In this case increase the temperature of the AC to a level more comfortable for you. - There's mold on the AC which can cause headache, in which case you should have the AC thoroughly cleaned and serviced.