What's the trick to getting the interior blower fan to work???

[chrisbruck]

Newbie 911 owner..... The fan I'm referring to is the one for fresh air in the cabin. The fan itself is mounted in the back of the trunk right up where the wiper motor is. I've got working A/C so that blower works fine with the two knobs by the shifter. If I pull up the red "ejector seat" levers on the floor and turn the rotary knob down there, the blower in the engine bay kicks in fine.

But if slide the fresh air levers all around on the dash, that fan doesn't seem to come on with any regularity. I'm thinking there may be an issue with the fan or switch. It's come on once or twice before so it does work but I have no idea what combination of positions I had all the other levers in.

Does it only come on when the other levers / blowers are in a certain position? I had the fan lever all the way to right (high speed position but no fan blowing), I banged on the motor itself in the trunk and then it kicked in fine, but when I climbed back in the cabin, played with the other levers / knobs / buttons to see which vents the air came out of, it decided to turn off at some point and not come back on. It didn't make any bad noises so I don't think it locked up or anything.

Just trying to get this darned thing figured out before I get caught in the rain and have the interior fog all up.

Thanks!

[steely]

This is from (Ian ? w/apologies) Mcarthur - I don't claim to be able to remember it LOL. I actually keep a copy in the glove box.

HTH.

[ossiblue]

The only lever that controls the fan is the top, right one--the one you correctly moved to the far right position. Moving any other levers do not affect the fresh air blower.

From what you posted, it sounds like you have a problem with the switch contacts or the motor itself.

[SiberianDVM]

The switch contacts for the fan are on the upper lever and are of a wiper design: a copper or bronze finger rides on a copper or bronze 3 piece semi-circle and makes contact at various positions in it's travel, triggering the fan speeds. Very primitive. Contacts are prone to corrosion, and are an A-1 ***** to get to. My whole control fell out of the dash the first time I tried to use it. New one not available and very expensive when it was, so this was one of the 1st projects I tackled. Took me 3 days, but it works now.

[twistoffat]

As Ossi suggested it could be corrosion. I removed the blowers last year including the footwell heat blower and gave them a clean up

[RSTarga]

he only way o defog the interior in rain is to turn the a/c on which dries the air out.

[luskesq]

I had the same problem and determined that the brushes were shot. Replaced and lubed the motor to cure the issue. Removal of the motor isn't a very difficult project.

Keith

[chrisbruck]

I was thinking it's a dirty switch or motor contact. Just wanted to be sure there wasn't a position on one of the other levels that disabled the fan from blowing.

So basically the 4 position control lever should always work regardless of everything else. Given this and the fact the blower has turned on, I bet it's a dirty contact or loose wire somewhere in the circuit.

Thanks for all the help!