Rather than the climate control computer, it has been suggested that the cause of erratic hot/cold high/low blowing (regardless of settings) is the "air blend door actuator" Does the following sound like a reasonable approach?
"The most likely cause has nothing to do with the blower motor. All the blower motor controls is the speed by which the air comes out. The cause for this is usually a little part called an "air blend door actuator". It is a module that sits just on top of the heater core housing that moves a door back and forth from the "cool" air coming from outside the engine compartment, and the "warm" air coming from inside the engine compartment. The gear that the door's shaft rides in typically gets worn out and reverts back to it's "default" position, which is in the middle. To fix it, you have to remove the lower plastic cowlings under the dash, then you have to remove: the upper cowling around the headlight cluster, the dashboard cluster, the radio, and the comfort controls. Then you have to remove: the radio, comfort control switches, speaker covers and speakers, and defrost vent cover. Then you have to remove the dashboard, by removing all the torx bolts you can find. There are also small trim bolts with the washers, and a few cap bolts on either end of the dashboard (2 up under the dash on the sides, that you have to really look for). Then the last part is to remove the 2 bolte that face up on the bottom of the steering column. THIS MIGHT REQUIRE 2 PEOPLE!!! When the steering column drops, the dash will come with it, but you need to tilt it back towards the seats while lifting it to pull it out. You don't actually need to pull it completely off, b/c to do so you have to disconnect A LOT of extra harnesses!!! Then to actually take off the actuator, it is located on the passenger side, right above the big black plastic box (heater core housing). You just disconnect, the harness, and then use a flashlight to see the 2 bolts. They are small, but not very visible. One is as close as can be to the top lip of the heater core housing (closest to you), and the other is directly across from it. There is also a tab that sticks up to help align it. The 3 are almost in a perfect triangle. You may need to move the big wiring harness out of your way. It will take you 5-8 hrs, but don't move too fast. Take your time, b/c if something isn't coming free it is still bolted somewhere to something!!!! TRUST ME!!! You will need a 6-10 mm and/or 1/4-3/8 sockets, 1/4 driver, some extensions, 1-2 flatheads, and 1-2 picks. GOOD LUCK!!!"