What problem cause this happen!?

Hi, I installed amp/headunit/speakers for my 99 honda civic.  Now, there's a little problem I am wondering about.  The headuint light/ac/defrost lights blinks by the little knob control the brightness.  When I turn the knob to certain angel, it goes normal no blinking but certain angle, it blinks.  I then cut the illumination wire with the headunit, the headunit works fine just without dimmer function no big deal for me.  But, still the ac/defrost lights(dome light? is it what those lights called?) still blinks when the brightness knob turn to certain angles, I guess the lights of hu and ac/defrost lights are connected all by one wire.  Anybody know what cause the light blinking? and how to fix it? By the way, the dimmer function for hu works, but it just blinks with ac/defrost lights when the headlights off/ brightness knob in certain angles, this I figured before cutting the illumination wire.

Sounds like a defective dimmer.  Probably has nothing to do with your stereo installation.  Go to a Honda dealer and order a new dimmer control.Support the12volt.com