For the last few days, the blower fan in my furnace/AC was running loudly, and now this morning, as I resolved to do something about it, it stopped running altogether. There’s a blower on/off switch mounted on a duct, and when I turned it on this morning, it just hummed.
My working theory is that a bearing failed on the blower wheel, and it fried the motor. The furnace is about 20 years old. Replacement of these parts looks like a DIY fix. Does anyone have other ideas? Am I crazy to think this is something I can do myself?
My other problem: I can’t find anyone to sell me a new blower wheel and motor? Home Depot doesn’t carry them, and HVAC supply places only want to deal with contractors. I may have to order online, and every day lost to the shipping process is a day when my wife just gets antsier to have it fixed.
My local HVAC supplier will sell to the public. The same thing happened to me and I went and bought a new motor, mated it to the old fan and off I went.
I can’t imagine anyone not wanting to sell you something in today’s economy.
No, but there are a few pitfalls. First is not just finding someone to sell you the parts, but also making sure you get the right parts. With 20 year old equipment I’m sure the parts are available, but probably with different manufacturers and model numbers than the original. Special order the wrong part, and a supply house may not want to take a return from a DIYer. Another pitfall is warranty, you basically won’t have one if you DIY. Of course, that assumes that you correctly diagnose the problem in the first place. Calling a HVAC guy in to fix it solves all those problems. It also takes care of your biggest problem: The Wife.
If it’s a belt-drive blower, take the belt off and try to start the motor. If it still hums and doesn’t spin, then the blower fan and its bearings are probably OK, but deserving a little oil.
Look on the motor itself for oil ports and give it some oil. Usually these are either holes trimmed out with a ring or spot of red paint, or even explicitly labeled “OIL” near the shaft. There should be one at each end of the motor, unless it’s a “permanently” lubed motor.
Put the belt back on and spin the blower by hand a few times. If you’re lucky, you just needed some oil and all will be well.
Another possibility is a dead start capacitor.
However, chances are good with a 20-year old system that the blower is a direct drive, and that it’s also a multi-speed DC drive like mine is. The electronics are much more complicated than the one in Grandpa’s furnace and are not at all DIY-friendly. You will not be able to pick up one of these at Home Depot, so the quickest route to domestic tranquility is probably going to be to call the local HVAC guy.
Thanks to everyone for the adivce and caution. It is indeed a direct drive. I may not have to deal with wiring issues, however, because the wiring on the motor plugs into a molex. Is that the right word – a power connector like one sees inside a computer.
I have seen parts online that describe themselves as replacements for my part numbers. Still not sure if I can find anything locally, though.
First you say the motor just hums.
Can you turn it by hand with the power off? If so motor or if it has a cap maybe the cap.
Look in your area for an appliance parts store. Give them model number of furnace and motor or take the motor and any cap in to the parts store. REMEMBER DISCONNECT THE POWER FIRST.
If the unit has an electronic board you may have some trouble just changing the motor, but you said the unit is 20 years old so you should not.
I first disassembled the blower to extract the failed motor. Googling the model number printed on the motor led me to several suppliers of replacements. $34 and 5 days later, the new blower arrived by UPS. It was a simple matter to re-assemble and re-connect everything, which now works as it should.
I took the blower assembly out last night and ran it while on the floor. The wheel spins freely when there’s no power, but when there’s power, it locks up. I’m definitely thinking new motor.
I have found a motor online that is described as the replacement for my part number. Here’s the wrinkle: The old motor had no capacitor, but the new one requires one. Apparently there are two extra wires on the new motor.
Can I just buy the capacitor and plug it in? Would this require rewiring anywhere else in the system (if so, I’m probably over my head). Also, since there was no capacitor on the old motor, there is no pre-existing site for a new one. Can I tape the new one in place on the blower housing with duct tape, or do I need to go to the trouble of drilling holes for sheet metal screws and strapping it down?
motors that require a capacitor to start have the place to mount that inside or onto the motor housing. no rewiring or making a place to mount it.
sometimes the capacitor is small and within the housing cylinder of the motor near where the wires go into it. look at your old motor to see if there is a capacitor there. you may need to only replace that.
are you speaking of a replacement motor with no housing?
motors that require a capacitor to start have the place to mount that inside or onto the motor housing. no rewiring or making a place to mount it.
sometimes the capacitor is small and within the housing cylinder of the motor near where the wires go into it. look at your old motor to see if there is a capacitor there. you may need to only replace that.
Weird that a replacement is physically and (internally) electrically different. Sounds like you found a semi-universal replacement - yes, it bolts into the same holes and yes, it spins the fan, but other than that, it’s different.
You need to hold the cap securely. Duct tape would probably fail by the end of this year. Is there anything you can zip-tie the cap to? Either to the motor itself, or to its mounting bracket?
Yes, I’d be getting the new motor but not new housing. My parts sheet that came with the furnace shows several related models, and some of those have a capacitor mounted in a particular spot on the housing. My model is listed as having no capacitor, and indeed the old motor does not have one and the housing has no bracket for one. The part listed as a replacement, however, does require a capacitor, and so I would have no place to put it.
BTW, as I understand it, it’s not a start capacitor, it’s a run capacitor.
gotpasswords, I might be able to zip-tie it to one of the motor’s mounting brackets. Thanks for the idea.