Make sure all the bulbs aren't bad. (it happens more than you'd think) If not try wiggling the light switch at the top of the unit. You can usually get the lights to at least flash. Take the top grill off and either unplug the unit or shut it off at the breaker. Take off the switch cover, remove the wires from the light switch. The light switch is all white, the fan switch has one black side. pop the switch down through the frame and then pop the new one up into the hole. Reattach wires and reinstall cover.
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Make sure all the bulbs aren't bad. (it happens more than you'd think) If not try wiggling the light switch at the top of the unit. You can usually get the lights to at least flash. Take the top grill off and either unplug the unit or shut it off at the breaker. Take off the switch cover, remove the wires from the light switch. The light switch is all white, the fan switch has one black side. pop the switch down through the frame and then pop the new one up into the hole. Reattach wires and reinstall cover.