Attention HVAC experts: What is wrong with my system?

Situation:

I have a two-thermostat system (one for upstairs, one for downstairs).

Starting today, the fan is incredibly loud for downstairs only. I verified it's the fan by turning it on by itself. At first I thought there was something wrong with the furnace, but apparently not.

What would cause the fan portion of the system to abruptly get loud? It sounds like a deep, loud humming sound, whereas before it just sounded like blowing air.

Anyone knowledgeable in this field have any idea what's going on? If I don't get answers here, I'll have to call a Russian down here on Monday and open the Jew wallet.

Quote:

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Originally Posted by Dan Druff

Situation:

I have a two-thermostat system (one for upstairs, one for downstairs).

Starting today, the fan is incredibly loud for downstairs only. I verified it's the fan by turning it on by itself. At first I thought there was something wrong with the furnace, but apparently not.

What would cause the fan portion of the system to abruptly get loud? It sounds like a deep, loud humming sound, whereas before it just sounded like blowing air.

Anyone knowledgeable in this field have any idea what's going on? If I don't get answers here, I'll have to call a Russian down here on Monday and open the Jew wallet.

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Im not an HVAC expert and im not exactly sure what kind of system you have - for example, are there two different blower fans for both thernostats? (I really have no idea how those types of systems work).

However, your issue sounds pretty similar to the one that I've recently had. Im wondering if your fan blower motor is shot. If the blower motor is making a loud humming or whining sound, it may be on the verge of seizing up and shutting down completely. The humming may be from a ton of friction inside the motor and it just cant take it any more - especially if the unit has some years behind it and/or the filter hasn't been changed properly over time. Dust etc can build up inside the motor and sooner or later shut it down.

Fletch:
Hey! It's all ball bearings nowadays. Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads, and I'm gonna need 'bout ten quarts of anti-freeze, preferably Prestone. No, no make that Quaker State.


Literally “sounds” like the bearings in your fan are worn. Prolly been running nearly nonstop for years. Same phenomenon as noising bearings in your car.

PositiveVariance prolly had worn bearings then his fan seized up. Just wear and tear.

I concur with the group. Likely the blower motor. They go out periodically. A humming noise is the first sign.

Probably just need to replace the fan motor. I had this happen a few years ago. The HVAC company quote was $800 to replace it. I looked up the motor and was able to buy it online for $200. I replaced it with an hour of pretty easy work. Spent most of my time getting comfortable with what I was looking at and doing. In total I probably touched ten or less screws/bolts. I'm sure an HVAC tech would have swapped it in 20 minutes or less and they would have paid less than $200 for the motor. You could always call in an HVAC company for a free estimate and they'll tell you exactly what is wrong and then look it up on youtube to decide if it's worth fixing yourself.

Yeah, the bearings are in the motor and you swap the motor.

YouTube is god. Replacing it might be kind of fun. First Druff will have to buy tools though.

over the summer a squirrel made a home for a short time in my dashboard. Right over the fan. It wasnt there long because as soon as I put the ac on the 1st time the thing ran out of the dashboard up my leg on its way over my head and then stopped at the back windshield. I was so thankful it didnt happen while I was driving. Once the thing came out the fan was still making a noise so I took the fan out of the dash and out popped 6 baby squirrel. If you're able to see the fan or easily access it is it possible there is something in there obstructing it? I'd start there before I considered hiring anyone to replace a fan that might not actually be broken. This being said I know not a thing about these systems only that a blowing fan making noise sounds like more an obstruction to me. And my car smelled like death for about a month. I was very close to trading it in because of this but it finally went away.

I was somewhat surprised at the cost. Much more reasonable than I thought...
Called out an HVAC company.
The motor was $225. Labor was only 1.2 hours.
Mine went out during the summer and they “Weren’t able to make it out the same day.” However, if I wanted to cover the overtime rate they could be here within a couple hours.
Instead of about $120 labor it was $180, which I had no issue paying as it was over 100 degrees. Luckily the guy had the part on his truck and went right to work. Total about $400. I was a happy camper.

Every time there is an issue with the A/C unit, I think shit is this going to be it? Did it take its final dump and go out? Especially as a unit gets older, it definitely crosses your mind.

You can squirt some wd40 (caution flammable) or oil where you would assume the bearings are located if that don't work call an expert.
I'm guessing you need a blower and it's not easy to change.

On second thought skip the wd40 call an expert, there's dangerous hi voltage capacitors and all kinds of crazy shit.

Quote:

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Originally Posted by Entropy

You can squirt some wd40 (caution flammable) or oil where you would assume the bearings are located if that don't work call an expert.
I'm guessing you need a blower and it's not easy to change.

On second thought skip the wd40 call an expert, there's dangerous hi voltage capacitors and all kinds of crazy shit.

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Yeah, definitely dont do the oil thing

At best: you might gain a day or two of no humming - and that is if you can get oil right in the right spot. Spraying the oil right where it needs it is virtually impossible though the way the motor housing is designed.

At worst: you will make a mess everywhere and possibly fry other electrical components. Even if it doesnt hurt anything electrical, you just made an oily mess everywhere that will be a great surface for dust etc to stick to and build up rather than normally blowing through the system.

Also, I dont know how old your system is, but you should also verify if the system is under warranty at all or not. Some warranties can go for several years.

Mine covered the part but I had to pay for the labor. The system is about 5 years old

https://youtu.be/f3qsgfUBImM

Motors for HVAC systems fans are probably similar to furnace fan motors

https://youtu.be/WkHgeTITioE

Quote:

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Originally Posted by Sanlmar

Fletch:
Hey! It's all ball bearings nowadays. Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads, and I'm gonna need 'bout ten quarts of anti-freeze, preferably Prestone. No, no make that Quaker State.

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I thought the only dodgy system todger had was his immune system