This is for a 1990 Integra with AC.
By the way, if yours melted and took the switch with it, the switch has 2 sets of 3 snap clips at the rear, can be disassembled and melted plastic carefully removed. The switch is removed by carefully prying the entire rectangle off after removing the knobs, 2 screws and it is out after the wire harness is removed. You should only need to remove the rearmost section, disassembling the rest can be fussy and is proably not needed unless debris has to be removed.
Disconnect the battery!
Remove the cover under the glove box, 2 screws and five internal hidden clips, carefully pull towards you and maybe up a bit. Pull the glove box too, 2 screws under pop out covers and two at the top at the latch bar.
Revove the 2 bolts on the right end of the metal plate underneath the cover you just removed, you will need the clearance.
Remove the screw at the top of the metal band covering the joint between the evaprator housing on the left and the blower housing on the right. Work the band loose at the rear, look to see how it hooks on.
The housing has three screws, one on the left side near the top, one at the bottom on a metal plate screwed to the firewall, and a third on the right side.
Remove the blower connector, the resistor (I assume) connector in front of the plastic grill of the housing and the connector(s) on the right side of the housing. Disconnet the drain hose (I still am not sure where mine went at the firewall).
You will NOT be completely removing the housing, so the connector at the extreme rear and the wire to the evaporator housing need not be removed, just don't stress them unnecessarily.
Work the entire housing free, you will need to move it a bit to the right side to clear the plastic overlap with the evaporator housing where the metal band went, look at that spot for the hangup. You should then be able to bring the entire housing forward, mostly moving it on the right hand side.
You should now be able to get all 3 blower motor bolts out and drop the blower motor and fan assembly out. Take off the fan nut and carefully lever it off by using screwdrivers on the right and left so you don't damage it.
Reverse it all to reassemble.
The instructions above are pretty good. I just finished replacing my blower moter. Here are a few things that might help you:
-There is no need to remove the entire assembly. You only need to pull out the bottom of the assembly so that you can access the bolts to disconnect the motor.
-Unless you have an original manufacturers part, the motor you purchase, if it is like mine, will have two wires coming out of it vice the plug that the original has. In order to deal with this, I took apart the old motor, pulled out the plug assembly which had two wires attached to what I believe were magnets, cut off the magnets and connected those wires to the wires from the new motor. Then I was able to just plug the connections together. I used wire nuts and electrical tape to ensure the connections stay together. It works great now