Replacing a Fan Blade: Finding one even if the original is obsolete

So your fan blade is broken/cracked/out of balance, etc. And your technician comes out and says the blade for your unit is obsolete, with no replacement so you will have to replace your entire system. This is a very common scenario. Not saying that all techs are shady and are trying to take advantage, but it does happen. Sometimes they legitimately just can’t find it, but you really never know.┬áSo keep your guard up, and if this happens to you, know that there is a replacement out there for you. Follow along and I’ll guide you through the process.

When replacing a fan blade, the first and best method for finding the right one for your unit is going to be by using your equipment model number or a part number if you can find it. This is the easiest way to reference what would be the direct replacement. Now, let’s say your model number is faded or the blade does not have a part number labeled on it. You are still not sunk. At this point it becomes a matching game. There are 5 key bits of information required to find a replacement.

Those bits are:
1. Diameter across the entire blade
2. Number of blades
3. Direction of blade – Clockwise or Counter Clockwise (Read on to learn how to determine this)
4. Pitch of the blades (Read on to learn how to determine this)
5. Hub or Bore size

Once you can provide this information, finding a replacement is a snap. And they are not difficult to install. Just one simple set screw. So when removing the old blade you would just have to unscrew that and slide it off of the motor shaft. Now, sometimes the blades from years of being beaten by the elements will get frozen to the shaft. It will take some elbow grease, but you can remove it by carefully tapping it at the hub toward the face of the motor, and once below the area it was frozen to, you can use some sandpaper and sand the shaft til it becomes smooth again. After that, apply some lubricant to the shaft like WD-40 and the blade will slide off like butter.

Determining direction of blades:
This is pretty simple. Using a tactic known as the “Sandbox Method”, you would hold the blade out in front of you flat, holding it by the hub, and drop it into a sandbox laying flat. If you were to hold the hub and spin it, which direction would it be going to where it would dig into the sand? Yes, it’s that easy. And no, you don’t have to go to the park to do this, as long as you can visualize the same thing.

Determining pitch:
The pitch is the degree to which the blades are angled. This is a bit trickier than the sandbox method. The best way would be to use a pitch guage, but if that is not available you can try using a protractor. Or, if you have a local refrigeration supply nearby, they might be able to gauge it for you.

So as you see, if someone tells you your part is obsolete , whether that be a fan blade or anything else, there is a very good chance there is a replacement out there somewhere. As long as you have the right information, your luck stands to be pretty good.

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