I've done some searching and gotten a pretty good idea but I wanted to ask before I dig too far.

I have an 85 -se with the AC removed. Anyway, about 80-90% of the time my heat works great. The other 10-20% it doesn't work at all. The lights still light up and you can hear it switch vents, there just is no air coming out at any setting. Drive it a few times and eventually it'll come back on and work for quite a while. But every once and awhile it'll shut off again (usually when it's raining )

Is this an issue with a switch, or maybe the blower itself? What's the MOST likely cause?

 

Does your blower motor stop and start spinning or does it run and the air just stops coming out of the vents.

 

If it is the blower quitting on you (on any speed), check the brushes in the motor. I had basically the same thing happen until the blower quit totally. I found 1 brush was completely gone; the other was down to almost nothing. Got 2 new brushes from a starter/alt shop (~$4). Soldered the new ones on, and everything was golden. The motor takes (2) 1/4"x1/4" brushes. If you replace the brushes, clean the commutator (part of the motor that the brushes ride on). A pink eraser works well for this. You can also clean the motor out with a spray made for cleaning electric motors. You might be able to find something at RadioShack or at a Hobby Shop that deals with R/C cars.

 

I'll give that a swing. The blower stops entirely, the air is not blocked. When it stops, literally nothing happens.

thanks, I'll report back next week when i get it done.

 

take the blower out, tap it on a hard surface, you won't believe how much crap has accumulated over the >>>DECADES<<<

next check the brushes.