Blower problem?


Old 08-27-02, 08:24 AM
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Blower problem?

I have a Carrier 58PAV Furnace that is starting to make a rattling noise from the blower housing. The unit is approx. 3 years old.
I had an AC Service company take a look at it a few weeks ago, within a couple of minutes the repairman told me the Blower Wheel was worn out and needed to be replaced. He didn't even try to realign the blower wheel to the motor or examine the motor.

So, I called another company to take a look and they spent an hour examining the blower housing and the motor. He took the motor out of the housing, realigned everything and put the blower housing back together. He informed me the blower wheel is fine and is not worn out ( which he found a little amusing ). He could not find any problems with the housing.

So my question is: Do blower wheels or blower housings go bad OR was the first AC repairman trying to sale me something i dont need? How can I tell if the motor is going bad or causing the blower wheel to rattle?

After two weeks of the rattling getting worse, I have no clue what to do to get it fixed. I finally decided to pull the blower housing out, took a good look at the blower wheel, spun it with my hand it ran really smooth - appeared to be aligned. The rod connecting the blower wheel to the motor seemed to have a little movement which could cause the rattle. However, I am no expert, I am just trying to isolate the problem. I have noticed that when the motor is running at the lower speed, the system does not rattle.

Has anyone heard of "natural frequency" vibration? Could this be causing the problem with the blower motor & wheel? If so, how can this be fixed?

Any suggestions or advice is greatly appreciated.

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Old 08-27-02, 09:53 AM
lynn comstock
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Blower noise increasing over time.

The noise could indeed originate in the blower wheel. The vanes/blades are crimped to hold them in place. If any of the crimps are loose, strange noises can be produced. Try to wiggle the vanes near the crimp points on each and every vane. There should be ZERO motion. "Worn out" could be an inappropriate description of this problem. This condition is such that it will worsen over time with increasing rattling noise...and may even eventually come apart.

Last edited by lynn comstock; 08-27-02 at 05:07 PM.
Old 08-27-02, 10:46 AM
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Am I correct in assuming that the problem came back after the second guy worked on it? My first suggestion is to look for a loose blade as Lynn said. Blower wheels are often balanced by clipping a piece of metal onto one of the blades. Is there a spot that looks like a clip used to be there? Any dirt buildup? Unusual dirt buildup patterns could cause the wheel to be unbalanced. Is the setscrew tightened down over the flat part of the motor shaft? What kind of movement does the motor shaft have? Up/down or in/out?
Old 08-27-02, 11:57 AM
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bigjohn, yes you are correct, regarding the problem coming back. After each repairman, the problem came back within an hour of them leaving. When both repairmen looked at the blower housing, the problem appeared to only occur when the blower motor was on high, when it was on low, no rattles. But after two weeks, the rattle is extremely loud and occurs whenever the air conditioner is on.

The metal blades appear to be secure, and I did notice two metal clips on each side of the blower wheel. As far as dirt goes, there is minimal dust on the blades, but other than that, there is not any buildup of dirt.

Also, the setscrew is tightened pretty good, but the motor shaft has a slight movement - in/out. When I move the shaft with my hand to see how much movement, I notice a slight rattle in the motor. I would estimate the movement to be around 5mm or so. And of course, when the shaft moves, so does the blower wheel.

Someone else told me about "Natural Frequency" vibration ( whatever that may be? ), which could cause this problem. And was told that I should move the motor as close to the blower wheel as possible.

Thanks for the advice
Old 08-27-02, 02:17 PM
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No, you want the blower wheel centered in the housing side to side and I would leave the motor in the belly band where Carrier put it. A little in/out movement is normal. If you're hearing a rattle inside the motor when you move the shaft around or when you spin it by hand, then there is probably something amiss inside the motor. It could be a bearing that is going bad, maybe a spacer or thrust washer is broken or bent . The beaing races are pressed in and maye one of them is spinning in it's housing. It sounds like the motor needs replacing. It's a job that's not beyond a handy DIY. Remember our rule: new motor-new capacitor.
Old 08-27-02, 05:39 PM
lynn comstock
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The description of the noise as RATTLING makes me think the blades are loose.

I also imagine that the rattling is too fast to count the individual noise events. With loose blower vanes I expect an almost continuous noise.

1) ASK the first tech exactly what he saw wrong with the blower wheel, and ASK if he could show you the defect that he saw. This should cost nothing.
2) Ask if they will guarantee their solution. I suspect the wheel as the problem. Motor bearings rarely make a rattling sound continuously.
3) Did you FEEL each and every blade for movement at the crimps? A visual inspection is not enough.
4) Do not wear loose clothing around moving parts, and be CAUTIOUS of electrical hazards also. With that in mind and with the blower on, CAREFULLY press the HOUSING with your hand to see if the noise changes and feel for vibrations. Also press on other parts of the air handler to see if the noise changes. Pressing on the end of the motor may also affect the noise. If the vibration and noise do NOT change, the wheel itself is the most likely source of the rattling noise.
Old 08-30-02, 01:09 PM
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Anyone know how much a new blower wheel costs, for a Carrier 58PAV furnace? Just a rough estimate. Or does anyone know of a website that I can use to purchase one from?
Old 08-30-02, 01:47 PM
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You could try I don't know whether they will sell to you or not.
Old 08-30-02, 07:23 PM
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I am just curious about the retail price of the blower wheel. Today, I had an AC company come out and replace the blower wheel for $233. This included cost and labor with 1 year warranty. I just want to know if I was overcharged. It did fix the problem listed above.

Also during the installation, I asked the technician about installing new thermostats. I wanted to upgrade to programmable thermostats, so I asked him what would I need to do to install new ones. I informed him that I planned on going to Home Depot and picking up two new ones and installing them myself. He then proceeded to tell me that since I have a two zone system ( trolAtemp MABS EZ-2 ), I would probably not be able to get any thermostats from Home Depot that would work with that two-zone system. So, I proceeded to ask him if he had any that would work and how much they would be. He quoted me approx. $250 for each thermostat, which would equal about $500 for both, which I clarified with him. And promptly I said "I guess I dont need them since they are that expensive." So, I can't imagine two thermostats costing $500.

Well, what I neglected to tell the technician was that I bought two new thermostats from home depot approx 6 months ago ( Honeywell 3200 ) and had planned to install them this weekend. All I wanted to know from him was if there are any special instructions for installing new thermostats for my system.

Since the tech told me that any thermostat I buy from Home Depot would not work with my system, I started to get worried. After the tech left, I immediately called Honeywell Customer Service to get some answers. I spoke to a nice lady and proceeded to tell her that I was concerned that my new thermostats would not work with my system and needed her to validate that. So, she looked up the model of the new thermostats and told me that I needed to call TrolAtemp directly and ask them ( they are a subsidary of Honeywell ). So, I called TrolAtemp and spoke to customer service and told him my dilema. He informed me that I should have no problem hooking them up and even helped me over the phone. Told me which wires ( 4 wire system ) to hook up. Within 15 minutes had both thermostats replaced and working great. So, the AC tech flat out lied, just to make a sale.

If you are curious what AC company this is, it is Frymire Engineering out of Dallas, TX. The only reason we used them, was they installed our AC unit when we built our house three years ago. I figured we could rely on them to fix our unit ( see original post above ).

Thanks for providing great feedback..
Old 08-31-02, 08:25 AM
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Unhappy Blower wheel cost

I had to replace one about 4 years ago and the cost for the wheel was about $35.00 at Johnstone supply
I took the old one in (it was rattling too LOL)
They didn't have the "original" but the "generic" they sold me looked a little different (a bit beefier BTW) and worked perfectly
It took about 30 minutes to change (would have been quicker if I would have done it before)
I think the guy just didn't want to mess with the thermostats and thats why he quoted you so high.
It's common for contractors of all types to give a high quote if it's a job they don't want to do.
Maybe he really thought you needed special thermostats ...

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