How to Rejuvenate a Box Fan




About: yawn....

Many people throw fairly new box fans out well before their time. Like most small appliances, people don't take the time to clean them, even though it will make them last much longer. I guess it is easier to put it out for the trash and spend another $20-$30. Whenever I see the towers of box fans for sale, I always wonder what happened to the ones people bought the year before.

After only one season a fan may be covered in enough gunk to give the illusion that the 'motor' is worn out, when really all that is needed is a good cleaning to keep it running for a lot more hours. I have often picked these up on trash day, and gotten years of use from them. Rarely I may have to replace a knob, but usually they are functioning, but the blade speed is about half of normal.

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Step 1: Tools

Just a few tools, though you can use many more for cleaning depending on the gunk level.

Screw driver
Paper towel
Dusting Brush
All Purpose Cleaner/degreaser
Finger Nail Brush
green kitchen scrubbies
steel wool

Step 2: Remove Front and Back Grills

These screws are usually very small. put them in your pocket or somewhere SAFE.
Sometimes a few can be missing OR the hole has grown too large to reseat tightly.

Yes, you can skip a few, usually you can leave off a side screw without TOO much noise factor.
but you NEED the top and bottom tightly screwed down of the vibration will make a hell of a racket.
scout around for replacements - you want short and fat threads.

Step 3: Remove Grill and Fit

You may have to unhook the power cord collar and remove the feet.
if the feet are missing you will have to dummy a replacement, or just make sure the fan is propped up, like in a window. Vibration at high speeds will make the fan walk and possibly fall.

Step 4: Brush the Motor

Remove all the material surrounding the motor, avoid spraying it with any cleaners.
Use a brush to remove the hair and gunk.
also wipe the struts.

Step 5: Wash Blades

Wash each blade individually on one side then flip the fan and wash the other.
I find that some blades resist degunking and a scrubbie pad is useful to remove the stuck on gunk.

If you leave it gunked and only remove the visual material, new stuff will quickly latch on and you will be just as bad off. You want to end up with smooth clean plastic blades, where things slide off.

Step 6: Clean Fan Grills

This is tedious and you will feel like cutting corners. If you have more than one fan to do, leave the 2nd until the next day. Use a brush for the solid matter. then spray with a degreaser/cleaner and then scrub with a nail brush or other firm bristle brush. Then wipe with paper towels.

The grids are NOT straight but beveled, and may appear clean if you look at them straight on, look at them from an angle and you will see they have four sides, you don't need it spotless, but get the area in front of the blades reasonable clean. You CAN do these in the shower, and use a long handled scrub brush, but you will still need to use paper towels to get in some crevasses.

Step 7: Reassemble the Fan.

Wipe the whole thing down inside and out.
Reattach the grills, the feet and align the power cord collar.
Turn it on, if the fan was not old to begin with you will find a world of difference between the speed of the fan blades before and after the cleaning.

I do this every season to my own fans and these $20 box fans last a lot longer then the manufacturers want them too.

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164 Discussions


Question 1 year ago on Step 7

Our cool master box fan just quit working it’s clean. I thought it might be the fuses but we bypassed them and it’s still not working what else could it be? Please help I don’t want to throw it away.


1 year ago on Step 7

I know this is an old, old post...
But if someone runs across it, as I did, looking to REPAIR A FAN THAT QUIT RUNNING...
Here are 2 tips I am adding.

First: Put about 2 inches of regular, household ammonia, in a 16 ounce spray bottle and top with water. (The best degreaser for dirty stoves,etc. and,costs just pennies.)
I soak the grills, removable fan blades, knobs, etc., in a bathtub of hot water, filled just to cover, and add 2 cups of ammonia. Clean as directed above.

Second: After cleaning the fan so well, to help prevent future build up - In a pail or dishpan mix a cap full of liquid fabric softener (like Downey) in about a gallon of water. Soak a clean cloth in it and wring it out. Use this to wipe all surfaces.
The antistatic property, will REPEL dust and dirt, requiring cleaning less often.
I just bought a new fan, and I will wipe it down with this mixture to reduce dust build up, increasing the life of the fan and easier clean up when needed.

wanna beco

8 years ago on Step 7

I never have to this. I duct tape a air filter to the back of the fan... I occasionally vacuum that filter. I have had them last decades. and I am very lazy. too lazy to clean like this.

1 reply

Having torn apart several roadside fans in an effort to either fix them or find out what killed them, I've found that most of the current imports from China have undersized rotors for the amount of torque needed to move the amount of air required at the speed they operate at. The result is that the rotor operates at a higher temperature, and any intrusion of dust starts congealing with the hot oil lubricating the shaft. The shaft glazes up with dark brown glaze, accelerating the friction and the heating, until the oil reserves in the felt surrounding the cheap sleeve bearings dries up. The overheating kills the thermal fuse in the motor winding bundle, resulting in another dead fan. The fan should take 10 seconds to wind down to a stop if it is a 15-inch fan. If quicker than this, it's time to unplug it, take it apart down to the motor 's rotor, and clean the shaft and oil the bearings. Remove the shaft glaze with 'wet' sandpaper of 600 grit by holding the sandpaper in a loose wrap around the shaft and rotating the shaft. I've been able to keep my cheap Aurora fan alive for years by catching the signs of slow startup or quick wind down, or squeaky bearings, and shutting down the fan until I've ripped it apart and cleaned and lubed it using regular 30-weight motor oil.

1 reply
ErinA50Gary Viveiros

Reply 1 year ago

Do you think canola oil would work lol thats all I have


4 years ago on Introduction

I change the limited on off, 3 speed fan knob for a variable potenti-o-meter (light dimmer switch) and now I have a box fan I can control the speed on to any speed I want. It's cheap and easy and even saves energy.

1 reply

4 years ago on Introduction

a bit diffrent that my metod... i found a box fan in the sumpster with a locked up motor... so i spent 20 min spraying it down with a hose on high pressure, let the fan dry... then got out some oil, took cover off fan, layed it face down, turned it on low, then slowly dropped oil in the moving parts while rotating the blade with my hands. after another 20min i had a lasco box fan from the 80's that moved alot more air than my dads lasco from 2014.

1 reply

Reply 1 year ago

Amen I love the old box fans!!


3 years ago

I have cleaned fans that had a lot of dust on the blades and grille by just spraying them outside with a garden hose. No disassmbly, left the motor in. I let it dry several days in the sun outside before using. I was concerrned about water in the motor but no problems years later.


3 years ago

I have a fan that the fuse blew on the plug how can i replace that


3 years ago

Does anybody know the customer service number for cool master box fan?

Is your fan a small 8-inch desktop? Most of the time it is a result of lousy bearings with so much play that the shaft rattles. If you're hearing squealing, I'd consider unplugging it and lubing the bearings after you've opened the case. There are several very small coarse-thread screws from the back that hold the front to the back half. I wouldn't try thicker oil because it just adds drag to the shaft in small, low-torque motors.


Reply 4 years ago on Step 7

Returning it to the store or manufacturer will make it a lot quieter.

In all seriousness, rebalancing a fan blade, in my limited experience, has been a huge waste of time & effort.

Fan noise usually comes from vibration. Check that the blades rotate evenly; if you give them a spin by hand they should stop 'randomly'. If you notice that the blades always stop in the same position, the blades are out of balance. Try to clean them, look for small breaks in the plastic, etc. You *can* counterweight them with small pieces of tape, but once they are out of balance its almost impossible to rebalance them. Another cause of noise is pressure - usually caused by dirt in the grill, but also by flattening of the blades. Look for evenness doing the spin test.