Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
Hello, my name is***** the fan speed only works on a few speeds then most of the time the issue is in the blower resistor module. The module fails internally between multiple resistors and causes this. You would need to test the module with a voltage meter in order to make sure that it is bad. It can be a controller issue but that is not as common. I hope this helps. Let me know if you need more help.
It is possible that there is an air door issue under the dash that is causing this. If you can hear the fan changing speeds then it may not be a fan issue. At that point the fan motor can be removed and the function checked with it out of the dash. If it is working then there is a problem in the dash.
You would need to start pulling the dash apart and check to see which air doors are moving. It may also be a vacuum loss causing this. I would check the vacuum hoses that are going into the firewall on the passenger side under the hood.
Let me know what you find.
Then the dash would need to be removed in order to check each one of these systems.
There is nothing that can be checked other that the fan motor without taking the dash apart.
Diagnosing a problem like this can be expensive as it is time consuming to remove the dash.
I definitely will. These older models do not have as many electronics as the newer models do but I will keep you informed.