HVAC blower motor resistor

The HVAC blower motor controller powers the blower and uses a variable frequency pulse to control the fan speed. It works for both heat and AC. When you select heat does the blower operate at all speeds? Have you checked the blower fuse? It is fuse 11-5 (30 amp) in the fuse block.
When you select a colder temperature what does the system do?

That sounds more like one of the temperature sensors are faulty. This car should have a built in diagnostic system to help you.
Open the hood and on the right side next to the washer fluid fill there should be two blocks with covers, pop the covers and you should find terminals. (Images 1-3) That is a built in code reader. They were on the the 94/5 850.

Take the cable attached to Diag A and put it into the #1 port on the B unit (image 4)
Turn the key on. The red LED should start to flash.
Now for the testing. There are three different modes you can test in. All modes flash the LED to indicate the codes with a pause between digits.
So a Flash - Pause - Flash Flash - Pause - Flash Would be a 1-2-1 code. There are 43 possible codes the system can store and it will show if something is at fault in the ECC or HVAC system.

Mode 1 will read out the codes stored in the ECC unit. To enter mode 1 you press the button on the A unit for about 1 second and the LED will flash the three digit codes. If you get a 1-1-1 code it means the ECC has not stored a code.

Enter that mode and look in the chart for the code(s) you find. Also post them here and there are tests/repairs listed for each code. (Image 5)

Mode 2 allows you to test the solar sensor (determines temperature and solar load on the system) and the speedometer link (if the car is moving it adjusts the heat/AC differently than setting still) To enter mode 2 you press the button twice for one second each press. The LED should start flashing faster. It should only flash 2 codes. 1-1-2 showing the Solar sensor is good and 1-1-3 Speedometer signal is OK

Mode 4 is a testing mode. You enter it by pushing the button four times, each press about one second long. It can be used to cycle the AC relay or to reset the servo positions after an actuator replacement. As you seem to have an AC control issue you could go into mode 4 and enter 1-1-1 within four seconds let the LED come back on after each press, that should cycle the AC relay five times ten seconds on and ten seconds off and indicate AC on the ECC panel as well.

Yes, a bad cabin temperature sensor can cause a loss of AC depending on how it has failed.
In this case it may not be the primary issue. I would try to blow it out as outlined below, clear the code and try the AC, if it works great if not try mode 2 again. The loss of the solar sensor could also cause it but I would expect to see at least one of the two codes show under mode 2.

It is actually a common issue with the aspiration type sensors used. They are a tiny fan that pulls air across a thermistor.
They pull in dirt, moisture, dag/cat hair and more. If you look up behind the grab handles you should see the intake ports, Take a flat screwdriver and gently remove the cover. Then use some canned air to see if you can blow the crud out of it. Cycling the key should enable the fan for a second or two as the system tests it.

This should show you the method. His does not have the testing unit yours has to clear the codes. On yours you set mode 1, then push the button on the test unit for five plus seconds. Release and the LED should come back on in three seconds. Then wait a bit and try to read the codes again. If you get 1-1-1 you are in business.
Www. YouTube. Com/watch?V=Fim4m2M9MiY

If the sensor fan does not free up you can use a small pick to see if you can move it and free it up, just do not touch the spring like item as it is the thermistor and can easily be damaged.
If nothing works then you will need to replace the sensor. To do that you need to get the headliner down far enough to get to the screws that hold it to the roof. That is the hard part as you need to remove a lot of trim to be able to move it without damaging the headliner.