Nearly 50 Years of Expertise

Whole House Fan Repair Guide

Expert diagnosis and repair solutions from Colorado's most experienced whole house fan specialists. Find your problem below and learn exactly how to fix it.

📞 Free Phone Consultation

Not sure what is wrong? Call us and describe your problem. We can often diagnose the issue over the phone and let you know what service you need. No charge, no obligation.

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🔍 Find Your Problem

1 I need a new belt 2 Fan hums but will not spin 3 Fan will not turn on at all 4 Fan shuts off unexpectedly 5 Fan has gotten noisy 6 Direct drive fan is very noisy 7 Shutter will not open or close 8 Shutter is damaged 9 Shutter rattles and vibrates 10 Roof mount fan is damaged 11 Fan is not pulling much air
1

I Need a New Belt

The belt on your whole house fan has worn out, cracked, or broken.

Simple Fix

Belt replacement is a quick, inexpensive repair. Replacement belts are readily available and the repair typically takes less than an hour.

Call us at 303-695-7911 to schedule a belt replacement. We will have your fan running again quickly.

Pro Tip from 50 Years of Experience

If the belt broke suddenly, inspect the pulleys for rough edges or misalignment that may have caused the failure. A properly aligned system with the right tension can make a belt last 10 to 20 years.

2

Fan Just Hums But Will Not Spin

You hear the motor running but the fan blade is not turning.

First, Check the Belt

Did the belt break? If the motor is spinning but the blade is not moving, you likely just need a new belt. See Problem #1 above for the easy fix.

If the belt is intact but the fan still will not start, the starting switch inside the motor may be stuck. This happens when the springs lose tension or dirt and corrosion build up in the motor. Try this:

How to Free a Stuck Motor

Follow These Steps
1
Open the shutter by hand, being careful not to damage it
2
With a stick, ruler, broom handle, or your hand, carefully spin the blade
3
Spin the blade in the proper direction, with the lower part of the blade scooping the air upwards
4
Remove the stick or your hand and have someone turn on the fan while the blade is still spinning
5
The fan should start up and run normally

If the Fan Does Not Run

You probably need a new motor.

If the Fan Runs But Refuses to Start Again Later

The motor is okay but the starting switch is not snapping into the correct position. This is due to worn springs or dirt and corrosion in the motor. Try this fix:

How to Fix a Sticky Starting Switch

Follow These Steps
1
Make sure the fan is turned off
2
Go into the attic
3
Spray lubricant (WD-40 or similar) into the air ports at the top and bottom of the motor housing for about 3 to 5 seconds
4
Tap the motor a few times with the handle end of a hammer or piece of wood, as if you were swatting a bug
5
Try the fan again

If It Still Does Not Work

You need a new motor. Call us at 303-695-7911 for a free consultation.

3

Fan Will Not Turn On and Makes No Noise

The fan is completely dead. No humming, no sound at all.

This is almost always an electrical problem. The question is: where? Work through these checks in order:

Electrical Troubleshooting

Check These in Order
1
Check for a reset button: Does the motor have a bright red RESET button somewhere (about the size of a dime)? With the fan switch turned OFF, push that button in AS HARD AS YOU CAN. If you did not hear a distinct CLICK, press it again, only harder. If it clicks, your motor overheated and should now work.
2
Check for a separate switch: Is there a switch somewhere that controls electricity going to the fan? Make sure it is on.
3
Check the main breakers: Go to your electrical panel and make sure the breaker for the fan has not tripped.
4
Check GFCI breakers: Look for GFCI outlets in the bathroom or garage. Press the reset button on each one. Sometimes the fan circuit is protected by a GFCI in an unexpected location.
5
If comfortable with electrical work: Carefully disconnect the timer and attach the wires together to bypass it. This tests whether the timer is the problem.
6
Test the switch: Carefully disconnect the switch and attach the wires together to bypass it.
7
Test the motor: If electricity is reaching the motor and it still does not run, you need a new motor.

Pro Tip from 50 Years of Experience

The GFCI check catches a lot of people off guard. We have seen fans stop working because a GFCI tripped in a bathroom on the other side of the house. Always check all GFCI outlets in your home.

4

Fan Turns On But Shuts Off Unexpectedly

The fan runs for a while, then stops. It will not start again for several minutes, hours, or even days.

What Is Happening

Your motor is overheating. There is an internal thermal shutoff in the motor that trips when it gets too hot. When the motor cools down, the switch resets so it will run again.

There are several reasons the thermal sensor might trip:

1
Faulty thermal sensor

The motor may not actually be overheating, but the sensor is tripping prematurely. Solution: replace motor.

2
Bad motor bearing

Spin the motor by hand and note if it spins freely or feels sluggish or makes a grinding sound. If it does not spin freely, replace the motor.

3
Bad fan shaft bearing

Same test as above, but spin the fan blade by hand. If it does not spin freely, the fan needs to be replaced.

4
Not enough attic ventilation

The motor is laboring too hard because air cannot escape the attic fast enough. This is very common in Colorado. Solution: add additional venting.

How to Test for Ventilation Problems

Follow These Steps
A
Open the attic entry hatchway
B
Place plastic on the floor to catch any debris that shoots out of the attic
C
Run the fan and see if the motor shuts off
D
If the motor runs without shutting off: You need additional attic ventilation. Call us to discuss options.
E
If everything seems fine but motor still shuts down: Replace the motor.
5

My Fan Has Gotten Noisy

The fan was quiet before but now makes noise during operation.

Work through these possibilities:

A
Recent roofing or siding work?

This might have blocked the roof, gable, or soffit ventilation. Try the attic hatch test to check. See Problem #4 for instructions. If it gets quieter, your vents are blocked.

B
Sound like tires on a rutted highway?

Your belt is cracking. Replace it. See Problem #1 for instructions.

C
Grinding or metal on metal sounds?

Check for metal shavings around the bearings. If present, the bearings are worn out and you probably need a new fan.

D
Pulley shifted or rubbing?

See if the pulley has shifted and fallen so it rubs against the motor housing or the fan itself. Readjust the pulley position and tighten the set screws.

E
Loose hardware?

Check for loose nuts, bolts, and screws throughout. If screws or bolts have come loose on the fan, it is often an indication that there is not enough ventilation and the fan is vibrating itself to pieces.

Pro Tip from 50 Years of Experience

Loose hardware is a warning sign. When we see bolts vibrating loose, we know the fan is fighting against inadequate ventilation. The fan is working too hard to push air into an attic that cannot release it fast enough. Adding ventilation often solves the noise and extends the life of the fan.

6

I Have a Direct Drive Fan and It Is Very Noisy

Direct drive fans have the motor directly in the center of the blade, either above or below it.

The Hard Truth About Direct Drive Fans

These fans are usually noisy from the beginning. The motor is directly connected to the blade, so there is no belt to absorb vibration. Other than checking the venting by opening the attic entry hatch, there is not much that can be done.

Sometimes the shutter is actually what is making the noise. You can try:

Possible Fixes to Try

Options
1
Try the attic hatch test. See Problem #4 for instructions. If it gets quieter, you need more attic ventilation.
2
Try injecting a very heavy duty grease into the shutter rivets. This sometimes helps with shutter noise.
3
Replacing the shutter is normally not possible because each company makes a different size shutter for the same size fan.

Best Solution

Replace the direct drive fan with a quality belt drive fan and install a good shutter. Belt drive fans are inherently quieter because the belt absorbs vibration, and the larger blades can spin slower while moving more air.

7

My Shutter Will Not Open or Close

The ceiling shutter is stuck in one position.

First: Are You Opening Enough Windows?

The shutter needs airflow to open. You should open windows equal to the size of the shutter opening in your ceiling. If you have not opened enough windows, try opening more.

If you have opened enough windows and the shutter still is not working properly:

Shutter Will Not Open

Try These Fixes
1
Standing on a chair, carefully open the shutter slats and look around for a spring that regulates the shutter weight
2
If there is a tension spring, adjust it by putting it into a different hole to increase tension (pull it tighter)
3
Check for debris in the shutter or paint that may have sealed it shut
4
If the problem persists, consider adding more ventilation to your attic

Shutter Will Not Close

Try These Fixes
1
Check for debris blocking the slats from closing
2
If there is a tension spring, adjust it by putting it into a different hole to decrease tension (loosen it)
3
Clean the pivot points and spray a small amount of lubricant on the pivot rivets
8

My Shutter Is Damaged

The shutter slats are broken, bent, or the frame is damaged.

Important: Shutters Are Hard to Replace

Unfortunately, shutters usually cannot be repaired. And here is the challenge: every manufacturer made the same size fans but made different shutter sizes! Finding a direct replacement is often impossible.

To replace an existing shutter, you need to find one the same size or smaller:

A
A larger shutter

Means you will need to remove the fan and recut and reframe the ceiling opening. This is a significant job.

B
A too small shutter

Means you will have some ceiling repair in your future, but it is still easier than reframing larger.

Information We Need for a Replacement Shutter

Please Have Ready
1
The size of the hole in the ceiling (measure the opening)
2
Is the hole completely clear, or is there an obstruction?
3
Does the original shutter sit flush with the ceiling or does it drop down several inches as a box housing?

Call us at 303-695-7911 with this information and we can discuss your options.

9

My Shutter Rattles, Shakes, or Vibrates

The shutter makes noise when the fan is running.

Most Likely Cause: Not Enough Attic Ventilation

This is the number one cause of shutter noise in Colorado. The air that the fan blows into the attic does not have enough opening (ventilation) to exit. The air pressure in the attic increases and pushes back against the shutter, causing it to rattle.

How to Test for This

Follow These Steps
1
Open the attic hatch that leads into the attic
2
Place a tarp or piece of plastic on the floor since you might get some insulation blowing out of the hatch
3
Turn on the fan with the hatchway open and listen to the sound of the shutter
4
If the shutter quiets down: You do not have enough attic ventilation. You should have attic ventilation that equals the size of the shutter hole in the ceiling.
5
Solution: Add more attic ventilation. Call us to discuss options.

If the Shutter Does Not Quiet Down

You have a cheap shutter that is not built to handle the airflow. Unfortunately, it is almost impossible to find a good quality shutter of the same size. Replacing the shutter with one that does not rattle usually requires complete reframing of the shutter hole and reinstallation of the whole house fan.

10

My Roof Mount Attic Exhaust Fan Is Damaged

The top blew off, is damaged, or the unit is not working.

No Replacement Parts Available

Unfortunately, there are no replacement parts for roof mount attic exhaust fans. These are the mushroom shaped units on your roof that run automatically.

The Solution

We replace the entire unit with a new one. Repairs are simply not practical for these fans. Call us at 303-695-7911 to schedule a replacement.

11

Fan Is Not Pulling Much Air Anymore

The fan runs but performance has decreased noticeably.

Several things can cause reduced airflow:

A
Recent roofing, siding, or insulation work?

This is the most common cause. The attic venting has probably been compromised and your fan cannot exhaust air properly. Solution: unclog the blocked vents or add additional attic ventilation.

B
Belt deterioration

Your belt might have deteriorated to the point where it is slipping and not turning the blade effectively. Solution: replace the belt. Do not overtighten. See Problem #1 for instructions.

C
Loose hardware

A screw or bolt may have come loose. Check the fastener holding the pulley to the motor and the fastener holding the fan blade to the shaft. Tighten all fasteners.

Pro Tip from 50 Years of Experience

When customers call about reduced airflow, our first question is always "Have you had any work done on the house recently?" New roofs, new siding, and blown in insulation are the top three causes of blocked vents. The workers often do not realize they are blocking critical attic ventilation.

What We Service

We Repair Both Types of Attic Fans

🏠

Whole House Fans

Mounted in the ceiling with a manual switch and a shutter that opens and closes when the fan is turned on and off.

  • ✓ Belt drive fans can often be repaired or adjusted
  • ✓ Sometimes customers find it more practical to upgrade to a quieter, more efficient model
  • ✓ Direct drive fans usually cannot be repaired because parts are not available
  • ✓ If the problem is with the timer or variable speed switch (not the motor), repairs are sometimes possible
🍄

Attic Exhaust Fans

Also called power ventilators. Usually on the roof (mushroom shape) or hidden inside the attic on an end wall. Runs automatically via thermostat. No ceiling shutter.

  • ✓ We typically replace the entire unit
  • ✓ Parts are generally not available
  • ✓ Motors rarely have accessible oil ports
  • ✓ Repairs are generally not practical
Need Professional Help?

Information That Helps Us Diagnose Faster

You do not need all of this information, but it helps us give you better advice:

❓

Nature of the Problem

Humming noise? Noisy? Does not pull enough air? Shutter will not open?

📏

Size of Fan

The diameter of the circle formed by the fan blades. Usually 24 inches, 30 inches, or 36 inches.

⚙️

Drive Type

Is the motor directly in the center of the blade (direct drive) or off to the side with a belt (belt drive)?

🎚️

Wall Controls

Timer? 1, 2, or 3 speed? Variable speed?

📋

Brand and Model

Check the label on the fan in your attic. Nice to know but not essential.

Good News

Most Fans Need Little Maintenance

Maintenance is usually not necessary for either a whole house fan or an attic exhaust fan. Sometimes a whole house fan will have a motor that has oil ports and is designed to be lubricated every few years. An attic exhaust fan almost never will.

In any case, it is usually impossible or impractical to access these ports in the attic and they are best left alone. Cleaning the shutter and blades every few years is often the only thing that needs to be done.

If your fan is having problems, it is usually a specific issue to diagnose, not a maintenance failure. Call us and we will help you figure out what is wrong.

Need Help With Your Fan?

Call for a free phone consultation. We will help diagnose the problem and give honest advice about whether to repair or replace.

Call 303-695-7911 Text Us

Serving Denver, Aurora, Boulder, Fort Collins and the Front Range since 1976

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