On my 93, from parents, have not had functioning A/C for years. No one can repair it. So have not used the blower fan all summer. Now it only comes on at level 2. I am not good at this computer stuff. Saw a posting via google with a photo I could not enlarge. Now on the website I cannot find it on the forum. Went thru 7 of 1448 pages suggested. Noticed someone said relays and resistors behind glovebox but the other contact said on driver side near wheel well.  Just changed the resistor and some other part on my 07 Chevy and thought this to be as easy to inspect for damage. Nope. Tried a spray into the slide area but that only made it slide easier.  Anyone know the location ?      Going back out now to get frustrated on the 85 GL that has another problem.   

The resistor pack is under the glove box in the air ducting.  Two screws and a connector.

I found this diagram a few years ago, hope it helps. It shows the locations of both the blower motor resistor and the blower relay.

another thought.............there may be an accumulation of old tree leaves and crap that can find its way to the motor and squirrel cage on the inside of the firewall. I thought I had a bad motor, but turned out to be an accumulation of junk. It is worth checking it out

It is worth looking at the blower motor fan. The original poster said the fan works, but only at level 2 of the slider switch. My experience with a dirty blower motor/fan was that it worked at all speed settings, but was noisy. Then it worked intermittently, and would sometimes turn on after I hit a bump. What finally convinced me that the problem was in the fan motor rather than a relay or resistor, was if I tapped the bottom of the fan, it would turn on. I just bumped my post from 2014 where I talked about removing and cleaning the blower motor. But on a car this old, if the motor fails, it could be dirt and crud in the motor or worn armature brushes and a worn/scored commutator.

I'm thinking the OP's heater motor problem may be the resistor or relay, but I'm not an electronics person.