Furnace makes a squealing sound

[NHL Fever]

Ok so for a few months, when the furnace fan cycles on to blow heat, it begins by making a horrible squealing sound which lasts for about 20-30 seconds before its just the regular blowing air sound. Fairly high-pitched. It does not happen every cycle. I notice it about once/hour.

Any thoughts?

[-SEEKING-]

(I'm about to show my ignorance of matters outside of HOT Miami.)

What's a furnace? Like a heater?

[IMINXTC]

Fan-motor is going out. Sometimes they can be fixed by replacing the bearings, depending on the make & model. But, generally, the whole unit (fan & motor) is replaced. It makes noise depending on what temperature it has reached.

It can eventually freeze-up.

[NHL Fever]

So the noise comes from getting too hot, or too cold?

The temperature outside here has been -20 to -30 celsius in the past few weeks.

Last service appointment shows as 2007. You don't need to service your furnace yearly right?

RIGHT???????

[IMINXTC]

The noise comes from the bearings. They will squeal at certain temperatures, but it doesn't mean too hot or too cold. Bearings are just shot.

A very common problem for HVAC fixers.

[TomH]

Drive belt from motor to squirrel cage.

Quick look at it to make sure it's not about to break, get the number off it (if you can) call NAPA with the number. If it's worn enough to where you can't read the number, take it off and take it to the NAPA dealer. (I know, you think NAPA is just for cars, but they have just about any type of belt. Including belts for clothes dryers)

Be sure and tell them what it's for, the V will be a different bevel.

Quick fix for the noise if the belt doesn't appear too worn until you get a replacement. A bar of soap held to the inside portion of the belt (where it makes contact with the pulley) will quieten the noise temporarily.

[NHL Fever]

Ok so one vote for bearings, one for the belt. Belt is probably easy to look at, will it be easy to examine the bearings?

Do I need to turn it off before trying to figure out how to open it?

[TomH]

Yes, initially, turn the furnace off. The blower wll be behind the air filter. take the air filter out to see the blower and motor.

I initially said it might be the belt, but there is also a blower that is direct drive, although it's not common. It's called a squirrel cage blower because it looks like, well a squirrel cage. Direct drive blowers will have the motor attached directly to the sqirrel cage, a belt driven will be obvious. If it's a direct drive, then SFASH will be the smart one, look at replacing the blower unit. Maybe you know a repairman that would be willing to replace the barings, but most generally they'll want to replace the unit.

If it's belt driven, and the belt appears to be in decent shape, you could check tension on the belt. A firm push between the pulleys should be able to flex a little, but shouldn't flex easily. Not quite as rigid as your fanbelt on your car, but you shouldn' have more than 1/2 an inch of play either.

Look at the V side of your belt. If it's smooth and shiny, it's been slipping and needs to be replaced.