Does this sound familiar to anyone? I've searched the forum and came up blank. I have a problem with my heater blower motor not working sometimes. Occasionally and only in cold weather I start the truck and the blower fan will not come on. I can wail on the dash a few times and it's back running. Moving the function switch back and forth doesn't help. Everything else works as it should but the AC has been dead for years. I replaced the blower motor last year but it didn't fix the problem.

What's interesting is that when this happens the fan is actually working when I turn the ignition on but then doesn't after I crank the truck - for this reason I'm thinking a bad relay of some kind or whatever turns stuff off during the cranking load or maybe something in the ignition switch? When I happens I don't have time to do diagnostics because I'm usually on the way to work and the windshield needs de-icing so I **** it into submission and go.

 

Sounds like possible ignition switch issue. There are a couple power wires that control systems that run through that switch. If it is faulty, it will cause issues, and with it acting up after you start it that leads me to believe it is a possiblity.

Have you tried wiggling the key after it starts. They can hang up a bit and not return to the proper spot and might be the problem. Might still need a new switch?

When I put a remote start in my truck, I had to tie into the right power leads on the ignition switch so the fan would run with the remote start working(to defrost the windows). If I hooked up the wrong wire, no fan.

 

Sounds about right. I will definitely try wiggling the key next time. We are in the pull a part pretty often so I might try a switch from a junker to see if that helps anything.