I have a 2008 E350. i've already replaced the blower motor resistor, and the blower motor itself. The blower motor switch works then it doesn't. If I take out the 50 amp fuse and put it back in the fan switch works. After a couple of times, it then won't work unless repeat the fuse removal etc.

Anybody know why this is happening? I could just replace the switch and see what happens, but figured I see of anybody here knows why this is happening.

 

You could have an issue with the switch and/or its connector----those are both known points of failure. Mine have almost melted, when accessed for inspection they're greatly deformed from heat caused by a relatively large amp draw over time.

Since you've changed the other parts its time to look at the last remaining parts that could be causing your intermittent operation.

HTH

 

Will ck out the switch and connector. How the switch even works at all just by taking out the 50 amp fuse and putting it back in, is what baffles me. I already sprayed an electrical cleaner for the contacts the fuse uses so I don't think its the fuse terminal.