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Discussion Starter #1
The blower fan on my 1989 900 Turbo convertible (named Nancy) eats fuses. I need to replace the 30amp fuse in about once a week. This raises some questions:

Is there a likely area to check for a short?

Can I put a fuse in with more resistance?

On a related note, the central vent on the dash board blows cool air, even if I have the heat on and heat coming out of the other two vents. What might cause this?

Thanks!
 

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Central air vent is always cold. Its the fresh air vent (well not too fresh, its heppa filtered first. The feature is almost one of the best things about the car!
 

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The fuse is protection. A higher rated fuse means that the bit to burn out will be harder to repair and may set the car on fire.

You're talking about the ventilation fan are you? Does it blow well before burning out the fuse? Is it in any particular position when it burns out? If you set the air distributor control to max flow {the position next to the 0 straight down}, does the fuse behave? This position bypasses the resistor pack so, if the fuse blows then, it's likely to be the motor. If the fan is not blowing well, it may have clogged bearings. Check this out {with the ignition switched off and the fuse out} by removing the ventilation air filter from the air intake under the bonnet and reaching up the duct to spin the fan. Be careful, the blades can be a bit sharp. If the motor bearings are clogged {as they can}, the blades will be somewhat stiff to turn. They should spin pretty freely. If they are clogged, it's dash out time to remove the fan. I did this once, removed the fan, stripped it, cleaned the bearings and refitted. Much better performance from the ventilation system after that...
 

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Discussion Starter #4
Thanks for the response, Cdaly.

With the fuse in, the blower works in every position.

When the fuse burns out, the blower only works on max flow, and only when the recirculate button is pushed. Does that tell anyone anything?
 

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The max position runs on a different (higher current) system, so, theoretically the two systems shouldn't interact.

I suspect that either the switch itself is bad or there is a bare wire somewhere.

Additionally, is the fan making any unusual noise? Like something stuck in it or rubbing against something? Could be a factor, but it's a stretch. A variation on the theme that cdaly pointed toward with the bearings -- if the fan is not turning freely, it could be an issue.

Once per week is what bugs me.... fuses blow on peak current, which means that the event is intermittent. These other things could be a factor, but there's something that happens every now and then to put it over the edge. I'll think on that for a while....:confused:
 

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Pull your stereo out and look for shorting wires. I just had the same problem myself. I had recently removed the fascia and little did I know I had left one of the stereo wires hanging a bit. It got caught behind the defrost actuating lever and little by little it ate thru enough insulation to cause a short. Took about 3 mornings of needing to run the defrost to appear. There are a bunch of wires behind there and my money is on one of them missing insulation and going to ground.
 
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