How to Troubleshoot Whole House Fans

If you have a whole house fan, you notice when it isn't working. A whole house fan is an energy-efficient way to cool the house when the weather and the humidity is low. It cools the home by pulling hot air out of the attic. You should be able to troubleshoot whole house fans yourself by following these steps.

Check Connections

To troubleshoot whole house fans, gather a screwdriver, a voltmeter, table lamp, lubricant (optional), and an extension cord. Carry an extension cord and small lamp into the attic, then connect the cord to another outlet.

Plug the fan in the extension cord, then try the lamp in the fan outlet. If the lamp doesn't work in the fan outlet and the fan runs in the other outlet, you have an electrical problem.

Run a voltmeter over the outlet to test for current, which beeps or flashes when it detects current. Make certain a breaker hasn't tripped in the breaker box. Inspect the wires on the  junction box and on the fan for damage, and test them with the voltmeter. 

Fix a Noisy Fan 

If you hear a clanking noise, the fan blades may be loose, unbalanced, or damaged. Turn off the power to the room and check the blades for loose parts or damage. Use the screwdriver to tighten loose screws on the canopy cover and mounting bracket, then straighten the metal blade holders.  

If the fan hums, look for the anti-hum feature. Some fans with fewer blades may hum on high settings, so change the speed to a lower setting or replace it with a fan that has more blades. 

A rattling fan means it lacks enough air. Consider installing another window, or open another window thirty-feet from the fan. Measure each blade to determine if they are all an even distance from the ceiling. Blades should clear the ceiling by thirty-feet, or it pushes air back into the shutter.  

Solve No Air Flow or Motor Runs But Blades Don't Turn and Burn Smells

A fan motor running, but not the blades, commonly means an issue with the belt. Detach the outer cover of the fan motor, and check for a loose or damaged belt.

Little or no air flow commonly points to exhaust problems. Inspect the exhaust for blockages, and the exhaust should lie near the roof ridge. 

A burning smell commonly indicates a problem with the motor. Replace the motor, and if that fails, oil the gears on the blade shaft.

Contact an HVAC contractor who offers air conditioning services if these troubleshooting tips don't work.