Can you provide some tech info on the up/down switch? Single-pole double-throw? like the gear motor switch? Are 1&2 (NC) connected then 1&3 when you press?
The black will be your common, if there are numbers next to the white wires, number 2 would be normally closed and number 3 would be normally open. So between the black and number 2 there should be continuity when not in use and when you push on the switch then black to 3 will be closed and black to 2 will be open. The wires that go to the gear motor are the 2 white which 2 would go to NC and 3 to NO.
When I press the button to raise or lower the power vent nothing happens. It is stuck in the up position. When I switch the fan control speed, the fan works fine. Is it a faulty switch?
This issue could be caused by a bad up/down switch, a bad gear motor switch or a possible bad gear motor. You will want to test the gear motor to see if it is getting power to it. If the motor is not getting power then check the gear switch to make sure that it is good. If faulty then replace.
When I press the button to raise the fan blower, it just makes a faint hum for 2 seconds and does nothing. Any idea what part may need to be replaced?
You will want to check to make sure that the gears are not binding. Other wise if it just hums and does nothing then it sounds like the motor may be faulty.