I have a roof mounted exhaust fan in my attic that died sometime in the last month or so. I tried to ignore it, but with highs in the 90s and lows in the 70s the upstairs was not cooling down at night. Then I got my $400 electric bill. Ouch.
I’ll do all sorts of home repairs but I hate heights and I don’t get on the roof. I called a roofing company that advertised attic ventilation. They wouldn’t repair the fan and the replacement estimate was $580. Ouch again.
I found a vendor through ServiceMagic that said he would replace the motor for $250, which still seemed expensive.
I finally broke down, went to home depot, and bought a replacement motor and thermostat and did the job myself. Parts ran $80 plus about 90 minutes in a very hot attic.
To figure out what is broken:
1. Check the circuit breaker and make sure it is powered on.
2. Turn the thermostat to its lowest setting to see if the fan will come on. If it does, everything is working OK, the setting was just off.
3. Beyond this, if you are not knowledgeable and comfortable working with electrical wiring, call a pro.
4. To troubleshoot the thermostat, carefully remove the cover. Using a voltage tester, make sure the black supply line is hot. Assuming it is, with the thermostat turned to its lowest setting from step 2, power should be supplied to the fan. If power is not going to the fan, the thermostat needs replacement (assuming the attic is warm of course). If power is going to the fan, then the fan motor needs replacing.
Here’s how you do it:
1. Shut electric off at breaker.
2. Take cover off existing thermostat. Pay attention to which black wire is connected to the hot wire and which one is connect to the fan.
3. Remove the existing thermostat.
4. The fan motor was held in place by metal strapping. Three screws held the strapping together. Support the motor and remove the screws. I had to bend the metal out of the way a little to get the fan blades past it.
5. The fan was connected to the motor with a set screw. Take note of the orientation of the fan to the motor so you can put it back the same way. Loosen the set screw with an allen wrench and remove. I thought this would be rusted in place but it came of easily.
6. Attach the fan to the new motor and tighten the set screw.
7. Place the fan back in the metal strapping and replace the screws. Double check everything to make sure the fan and motor are firmly supported.
8. Wire the fan to the new thermostat. The white wire from the fan will go the the white (neutral) on the supply wire. The bare copper from the supply will attach to a screw on the thermostat. The black (hot) wire will attach to one of the black wires on the thermostat. The other black thermostat wire will connect to the fan.
9. Make sure all electrical connections are properly made and place cover back on the thermostat.
10. Set the thermostat to a low setting.
11. Turn on breaker and test.
12. Once everything is working, adjust thermostat to desired setting.
I replaced the thermostat because I had the purchased the parts and already had everything apart. I used a voltage tester to ensure my thermostat was working ok before replace the (dead) motor.
