Heater Fan

I would replace it but i recently did my heater core and getting in there is a lot of work.

upgrade the stereo....

That was the first solution i used and it was good for a while but i want something better.

Not to be an ass, but there really are only those few choices. Replace it, don't use it, ignore it, or turn up the volume until you can't hear it anymore. It's not serviceable, and even if it were, that would mean you'd have to pull it out - something that you seem adamantly against.

Are you sure it doesn't just come off from under the dash? I've never had to replace one so I don't know, but I don't recall it being a part of the heater box (which I have had to remove to do heater core installs).

Maybe someone else knows that...

JS

What year of Mustang are we talking about? I just did a fan motor change on my 1991 GT and it wasn't much work at all. The fan motor can be replaced without removing the dash. It's a little tricky, and requires a bit of shoehorning at points, but I was able to do the entire swap in under an hour (excluding the time it took to go buy the motor, solder the old connector onto the new motor, wash out the fan housing, etc.) and only required a screwdriver and a small ratchet. You don't just pull out the motor, however, you pull out the motor and the plastic housing into which it is mounted. That housing is held on by a total of (I think) three small screws; two where it mates up to the rest of the ventilation system, and one at the top right behind the glove compartment door. You need to lower the glove compartment door down in order to see it.

Only thing to be weary of is that the fan motor designs changed somewhat over the years. The cooling tube that runs from the motor to the ventilation system is different depending on the year, but most parts places aren't aware of that. I had to use the cooling tube from a 1987 GT to mate up with the replacement motor I purchased. Easiest way to know is to compare your old motor to the new one. The motor gets indexed into the fan housing based on a series of holes drilled through the mounting flange, so just compare those against the large hole drilled in the side of the motor housing to see.

It's an easy enough swap, though, and the motors aren't particularly expensive. You might also need to buy a pack of push nuts to hold the fan blade on, since the one that's holding it on now most likely won't survive being removed. Failing that, you could always try just oiling the bearings on the thing. I don't think you can get at them without removing the motor, though.