I've searched already and found all the threads about losing certain speeds or losing all but the top speed of the blower motor. My problem is the opposite of what everyone else encounters. I have speeds 1-3 that work great, and the top speed(4)is the only one that isn't working. What should I be checking? I figure it's not the resistor, as I have read that the resistor is basically bypassed in the top speed. Also, I don't believe it's the relay, as wouldn't the relay being bad effect all speeds?