Today my blower motor wouldn't shut off even with key out. Replaced blower motor resistor now blower motor wont work. Don't know what to do now. Checked all fuses and they are good

 

year, engine

 

We had similar issue with blower motor remaining on sometimes with key out, sometimes blower motor wouldn't work at all (2005 Yukon). I decided for such intermittent to let the mechanic handle this, so I wouldn't be one to have Mrs. Cusser get overly hot as summer is 9 months here.

Mechanic replaced both resistor and blower motor, said he's seen where one can take out the other. Fixed fine, over 1.5 years now.

 

Blower relay stuck closed that's why it would not shut off. Replace the relay. It could be totally fried now after sticking.
Resistor only changes speed, doesn't turn it off or on. If it still doesn't come on after new relay than new resistor could be defective.

 

I've been down this road and read a lot about it. My 2013 2500 Suburban starting having trouble with the AC working intermittently. The Blower Motor always tested good, so I'd swap out the Resistor. It would work for a while, then it wouldn't. I'd try another one, and sometimes it worked, sometimes it didn't. I ended up putting a new AC compressor in it. Our problem was intermittent and the shop couldn't repeat the symptoms. So 1K$ later, new AC- that then eventually had the same problems.

Then I read somewhere about the battery cables/power cables deteriorating and it causing weird problems with your electrical system and sometimes with your AC and the Blower Motor and Resistor. I was so fed up with the problem (and so was my wife), I bought the best OEM Resistor and Blower Motor I could get, and I replaced all of the main power cables running back and forth from my battery under the hood. The dealership charged me a pretty penny for all of the cables (I think I did 4 different cables- positive and negative, one to the alternator, and one to the fuse box, and maybe I did the ground too). GM modified the ends of the cables connecting to the battery (the plastic sleeve goes back down the wire further now and helps prevent moisture from getting in the wire). This solved everything. I only did the Blower Motor because the truck had 160K miles on it, and it seemed to me if I was doing the Resistor one more time in addition to the dang wiring, I might as well do the Blower Motor. I have not had one problem with my AC since. Zero.

Not sure if this will help you, but it seems those power cables were prone to begin failing. What turned me on to that, is that my wife noticed that the intermittent AC problems presented themselves most often when it had rained recently.

Good luck. I hope your fix isn't as expensive as mine. But at least I got it done.