When I turn on my blower (any setting) the daytime running lights go out. This started as a random occurrence but now happens everytime. The blower motor and resister were both replaced with new parts 4 months before this problem started. I've checked the fuses (all good) and can't seam to find a relay.
Blower / daytime lights on 2000 Pontiac Grand Prix
It seems when you got the heater resistance is causing the problem have it replace maybe it was defective