Furnace Blower Repair

"Bob!! The furnace is making a funny chirping sound again. It sounds like there is a bird stuck in the fan - would you check to see if ours are in their cages!!"

The fan on the Williamson furnace was acting up again. It was time to do something. The bird joke was wearing thin on me so I got a droplight from the shop and headed for the basement. And it wasn't just the joke that was wearing thin, a broken furnace wears out my patience to the point where I begin needing a vacation at some Punta Cana resorts

The first thing I did was to locate the power switch on the side of the furnace and turn it to the off position. I then called upstairs and asked Arleen to set the thermostat to 90 to see if I had indeed found the correct switch! It did not respond with the usual swooooosh of the flame igniting so I knew I had indeed made it safe to work on.

This is a squirrel cage type of blower which is belt driven from a fractional horsepower motor. I could see that the belt was a bit loose but when I grabbed the driven pulley and pulled it from side to side I found that there was a lot of side play in the bearings.

I loosened the belt further and slipped it off the pulleys. It was cracked and looked like it had served its purpose so I made a mental note to get a new one.

Now laying on your side reaching into the bowels of the heater plenum to replace components isn't my idea of the best way to spend a Saturday afternoon so I began to poke around to see just how this thing came apart. I looked on the top wall of the blower cavity and noticed two distinct rails into which were slid two long pieces of angle iron. Mounted to the angle iron was the squirrel cage blower assembly. A quick check on the top side of the panel yielded two 7/16ths inch cap screws. I removed the screws and pulled on the blower assembly and sure enough it slid nicely in the rails. The only problem was that the motor was bolted onto the side of the blower assembly and the bx cable feeding it power was too short to permit full removal of the blower assembly.

I noted that the blower motor was held to the side of the blower by means of two bolts whose heads were slid into a long channel. I marked the position of the motor on the channel so that I could easily line up the pulleys later on and unbolted the motor from its mounting.

A quick trip to the local Grainger supply store had supplied me with the two blower motor bearings*, a belt and a shaft. The total price with all the hardware and a new belt was under 20 bucks. I disassembled the old bearings and shaft and slid in the new ones. The blower assembly slid nicely back into position on its mounting rails and the motor bolted back in place at the marks which I had made earlier.

A flip of the power switch and the blower ran like a clock - a quartz clock since there was no ticking - and no more birds either!!

* Part number 2A757, Dayton Mfg. - Grainger locator > Browse The Catalog > Blowers > Shaft and Bearings

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