perfectphoto

I have a 87 s4 that I have been bringing back to life. I can't get the climate fan to come on. There is no power to the switch or the blower and I by passed the blower and it runs fine with 12 volts applied. When I move the slide on the controller I hear noise from under the dash, it sounds like a electric motor trying to move something but I can't identify it. When I put it on defrost I see the blend door moving to divert air to the upper vents. I have check fuses and relay but just haven't had any luck. Sorry if it sounds like I'm rambling here, late night at a new years eve party.

Mrmerlin

replace the blower fan relay

Ducman82

the noise is teh HVAC blend door moving. sounds like bad relay or fuse. i have had fuses look ok, but the corrosion was just enough to keep the relay from activating

perfectphoto

I tried to swap out relays with another one that has a big 53 on it and it didn't do anything. Is the blower relay a different one than a 53?

Ducman82

should be the same. try jumping the relay, could be a bad connection or corrosion

Mrmerlin

replace the HVAC relay and then the X bus relay do one at a time