Yeh i know it an old topic and old truck but with 179000 miles i still love my burban. Just recently when i start the engine the front blower doesn't turn on at any speed. I can turn the **** through all speeds and nothing. I can leave it set to any speed 1-4, drive down the road and after a few bumps in the road it will turn on and all is well. The rear works fine. Ac or heat it is the same. I have been turning the ac button off till the fan kicks on to be safe there. Anyway today it snowed and no blower, bump or no bump. Raised the hood with the engine running and thumped on the relays on drivers side fender well, no luck. Checked a 50 amp blower fuse and it was good. Still no blower. Do i look under the dash on the passenger side for bad wire connections as i've read some where? What should i look at next?

 

yea if bumps make it work/not work then theres a good chance of a loose/bad connection or rubbed wire somewhere

 

I have 95 tahoe and had the same thing happen. I found that I was loosing the ground at the blower. I havent found where yet but I put a jumper at the blower and it works tell I tear into it.

 

Thanks, that will be my starting point, around the blower its self. If i make progress i'll report back with details.

 

Connect 12 volts to the blower motor and see if it runs. If it doesn't and you have to tap on the motor to make it run, then you have worn out brushes in the motor. The motor will have to be replaced if this is the case. I have replaced brushes before, you have drill out the rivets to get to it.