How to Clean a Furnace Fan
Improving Fan Motor Performance and Efficiency
Cleaning the fan on our furnaces is something that has likely never been done or we've paid significant amounts of money to have someone do for us. Neither has to be the case any longer.
Removing a blower assembly is not an overly complicated task and performing this maintenance has a nice set of benefits.
- Improves fan performance
- Increases fan motor efficiency
- Removes large amounts of dust from your system
- Lowers the chances of motor failure
- All of these equal less money
It's important to understand that all electrically operated devices work better when clean. When these devices work better, they also work more efficiently. The added insulation of dust on electrical components causes an increase in operating temperature and there is little that is harder on electrical components than high operating temperatures. Of course in this case, if the fan blades are caked with dust, you now have added resistance on the fan which causes the motor to work harder not to mention less space between the blades thus causing a lower output of air. The list goes on.
Direct Drive vs. Belt Driven
Today's furnaces typically run on a direct drive fan and motor assembly meaning the fan wheel is attached directly to the motor. A belt driven fan however has a belt that runs from a pulley on the fan to a pulley on an externally mounted motor. How the motor and the fan are situated in the furnace in this case can vary but you know right away if you see a belt in there, what you have.
The following steps will explain how to remove your blower assembly, clean it and of course re-install it without the use of any specialty tools, science books or money spent. Let's get started by using a direct drive blower assembly as our example. You'll be surprised how much dirt can stick to a fan moving at 1200 RPM.
Getting Into Your Furnace
Basic Furnace Structure and Safety
As you see in the picture here, the furnace is divided into 2 basic sections. The upper section is commonly known as the burner compartment but we will be focusing on the bottom section commonly known as the blower compartment. The blower compartment contains your blower assembly (fan, squirrel cage and motor) and typically your control board. In the case of a horizontal unit, the arrangement is basically the same however, in a down-flow system, these compartments are simply switched in most cases. Either way, the following will apply.
As we proceed, safety and care must be given to this task. Whenever working with electrical and/or gas burning appliances, you must proceed with caution. Not only does this help secure your safety but it also prevents causing more damage than good in our venture.
For removing the blower there are 3 main things that you need to be sure of:
- The power to the unit is off either by a switch or breaker panel.
- When pulling out the blower, know that the fan will spin freely so be sure your fingers are in a good location to avoid them being pinched or cut.
- Pay attention to the wires and parts that are attached. This is a sheet metal cabinet so there are edges that can compromise wiring insulation and/or damage parts that aren't properly set aside or handled.
None of this is meant to scare you away from doing this maintenance because as I said, it's not rocket science. I just want to be sure you're aware of the possibilities and that this is only beneficial to you, not problematic. If you become unsure of anything you face while working on your unit, do not assume anything. Contact a professional HVAC technician for your service.
Furnace Fan Removal PhotosClick thumbnail to view full-size
Steps for Removing Your Furnace Fan
- Be sure the power is off to the unit.
- Remove the doors on the unit to gain access.
- Remove the door switch if it's in the way of pulling out the blower. You should be able to take out the 2 screws holding it in place without disconnecting any wires.
NOTE: For those of you who are aware that this switch cuts the power to the unit once the door is removed, hopefully you know that power is still feeding the switch as well. This is why you kill the power prior to it entering the unit by the breaker or externally mounted switch.
- Dismount the control board. Again, this is usually only held in place by a couple of screws. DO NOT REMOVE THE BOARD FROM THE MOUNTING BRACKET. The bracket and all should come out once the screws are removed. You shouldn't need to disconnect any wires either but if you do, be sure to mark where they came from. There should be enough slack in the wires to set the board and switch off to the side while you work on removing the blower.
- Dismount the blower. There are likely 2 screws holding the blower in place. Aside from that, there are simply 2 "slides" where the top edge of the blower assembly slide nicely into that carry the weight of the blower assembly. With the screws removed, the blower should slide out nice and easy for you. Here is where you need to be careful with the wiring that is still attached and your fingers.
That should be it. It's out and ready for a good cleaning. At this point, it is probably quite clear as to why you should have done this long ago.
Tools for Cleaning a Blower Wheel and Motor
This will be nice to clean the blower cabinet while you're there too.
This is nearly a perfect fit to get in between those fan blades where most of the dust is.
This will be good for dusting down the blower housing and some of the furnace parts while you're in here.
3 Amp Fuses for Your Furnace
I threw in this little tidbit because keeping a few 3 amp blade fuses around the house can be handy and costs little to do so. On your circuit board, you will find one of these fuses that, though it's rather infrequent, do blow. It's easy to see if yours is blown by holding it up to the light...see the little wire passing through the plastic? If it's broken and there is a little burnt looking area, yep...it's blown. Not to mention that if it blows, nothing will be working on the unit whether it's heating or cooling season.
Fan Cleaning PhotosClick thumbnail to view full-size
Cleaning the Fan and Motor
There really isn't much to cleaning the fan in your furnace once it's out of the unit. Using a toothbrush or paint brush, you can clean between the fan blades, motor housing and squirrel cage. Your vacuum will be good to keep the dust down and suck up the clump of dust that gets left behind. Trust me when I say a clump of dust is very likely an understatement as you can see in this picture.
NOTE: Try to avoid pushing dust down into parts by using a pulling motion to swipe the dust and keep your vacuum near your brush to clean as you go.
Cleaning the air, saving money and it doesn't cost anything...sounds like a winner to me.
I hope this hub is helpful to you and shows just how important it is to see to it that you either clean your furnace fan or have someone do it for you. We all want to breathe easier and save ourselves money...this is just another easy, no cost way of doing so.
Questions & Answers
We have a heat pump. How do we clean the outside unit and inside furnace coil? I sneeze whenever the heat comes on.
I've written other articles on these topics. The coil is not likely something you can personally clean and may need to have someone come out to do.
How do I remove the furnace fan wheel to power wash it?
The short answer is typically the motor shaft runs thru the wheel and is held on by a set screw that you'll loosen to take it apart. Now getting everything out of the way so you can drop or slide the motor and housing out to do this is a bit trickier. I don't know what you have exactly but can say you have to pay close attention to how you take it all apart so you can put it back together correctly. It's not rocket science to take apart and put back together but if you don't take notes, pics, and/or pay attention to this dismount, you could have major problems. But your wheel will be clean. (Haha) For example, my circuit board is mounted in front of mine so I have to disconnect all the wiring and board before I can even get to the motor housing.
Is it a good idea to thoroughly spray the circuit board in the outdoor condenser unit with contact cleaner? I live in a coastal area where salt seems to build upon everything that is never rinsed somehow. I saw an HVAC tech do this one - really drenched it with some CRC contact cleaner. Is this a good idea?
Unfortunately, I'm not familiar with what is done in coastal areas...that said, CRC contact cleaner may be a little stronger than I might use here as opposed to a general electronics cleaner but maybe that's what is required for salt.
© 2012 Dan Robbins