I have two of these switches and they both are operating incorrectly. I use them to control bathroom fans in two separate bathrooms, but they both act the same. That is, when I push one of the time settings they provide only enough power to the fan to barely make it move. When I take the switch out of the equation and hook the two black wires up directly to each other the fan works at full speed. Are these faulty switches or do I have something wired incorrectly? (I can't imagine I have it wired incorrectly since I simply replaced the existing switch with this new one and attached the green ground wire to the other ground wires.) Help!

Leviton countdown timers have additional wire that powers internal electronics.
Leviton timers have red-black-white-green wires (or blue-black-white-green wires)

1) Regular single pole switch has 2 insulated wires. One of these wires is Hot from breaker, and the other goes to Load (fan)
2) Timer green wire connects to bare ground as you know.
3) Hot from breaker connects to timer black wire.
4) Load wire connects to timer red (or blue) wire.

5) Located in back of box are white wires that are twisted together and covered with wire nut.
These are Neutral wires. Connect timer white to these wires. This will power timer electronics.
6) If box does not have Neutral wires described above, then connect timer white to bare ground along with timer green wire.

7) Turn power ON and try timer countdown.
If timer does not work, then reverse timer red and timer black wire.

8) If box does not have neutral wires: Image on link below shows similar Intermatic timer:
Image applies ONLY when Neutral is not available.
http://waterheatertimer.org/images/EI210-wiring-full.jpg

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