[CatSkynr]

The easiest way is to put a volt meter on your fan connection. When it works, what is the voltage. When it doesn’t what do you read. With a stuck motor, you will see a dip in voltage (inherent current draw), but there will be V there.

My blower motor was junk when I bought my car. It only worked on high, and then every once in a while it would squeal. I removed the motor and replaced the shaft bushings (lots of slack was found). I found with the use of a file and some Autozone generic plastic bushings, I made a perfect snug match. Then I soaked the motor in Tri-Lube with Teflon and let it drip dry over night. Wiped it down and ran the motor outboard with a rag close at hand to fling the remaining lube, reinstalled and since then for the last 5 or so years never had an issue.

As for cleaning your switch, yes you can as long as the reed points aren’t shot. Usually they are fine with a cleaning and they sound fine being the low setting ‘does’ work sometimes. Best is electrical contact cleaner (Trichloroethane). You can usually find this at ACE Hardware or your local elelctro-nerd-hobby shops. Just pull the switch and spray inward into the shaft. Then run the switch through its contact points to break up any debris. Do this a couple times. You can use alcohol, but it is not near as effective in removing debris and oxidation.