power windows and blower sometimes not working?

[marshtgrade]

i have noticed over a few months my blower and power windows simultaneously go on and off from getting power. sometimes work all the time, sometimes turn off at low rpm, sometimes gets power again during higher rpms. the light for the switches go on and off while driving. sucks when i have windows down then park, i would rev a little and sometimes would turn back on sometimes not. changed fuses but no real change. i can live wit it sometimes, i just make sure my windows up before i plan on parking. i looked briefly in my bentley but i have very little electrical experience personally, and the wiring map can be a little confusing.

what to check next?

[Jalves619]

Unloader Relays K5 and K7 if I remember correctly.
Most likely those are good and you're having an intermittent grounding problem. Those relays are grounded through the starter. When the car is cranking it cuts power to the blower and windows in order to get full power to the starter. Easy solution is to ground the wire elsewhere and not try to roll your windows down while you crank the car.

[mr.vang]

try cleaning your fuse, non-bmw fuse has poor connection. it works for me thought.