First my heater only worked on high, so i changed the resistor. And it was working on all the speeds. Then I noticed that when i try to put it on defrost only or to change the settings it doesn't change, the heat just blows out of everywhere. About a month after we changed the resistor, I noticed the fan would work on all the settings except high. Now just a couple weeks ago it started to make a loud noise and it stopped working all together. You can hear it going but barely anything at all comes out of the vents. I let the truck run for about 45 mins and my windshield was barely defrosted.
Heater problems again on 1995 Chevrolet 1500 Pickup
sounds like your blower motor. if it draws too much current, it will fry the resistor which could be the reason for multiple failures.