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Blower motor vibration in a/c unit

My Carrier a/c unit is vibrating enough to shake the house. I replaced the motor and it made no difference. How can I check if the wheel is in/out of balance? What else can cause this?

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There are thin weights that can be added to the fan blades much like you can add weights to a ceiling fan blade and balance it out. Real simple!

Posted on Aug 29, 2012

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You already checked to see if the blower wheel is out of balance by noticing that the a/c unit vibrates. There is nothing else that can vibrate that badly.

Go buy a new blower wheel.

Posted on Jul 22, 2008

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You really cant check for it out of balance. not to mention you will never get it back into balance. The best thing to do is to buy another blower. the vibration will cause other problems including causing freon leaks in the evaporator coil.

Posted on Aug 29, 2012

  • JTran Jul 29, 2013

    Remove the whole blower unit out and place on a flat surface with the wheel face up; then use the small fan to blow air to the fins. While the wheel and shaft rotating, you can see the wheel out of balance, the faster the more vibration. To re-balance the wheel, you need to place a small tab on the fins at certain location and weight. It requires your skills and time. Noise is just one of its problems. Running out of balance for a long run will damage the bearing of the motor too.


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1 Answer

My Goodman model#A36-15 just started squeaking constantly. What would cause this to happen? It only occurs when the fan turns on.

Fan motor going bad
Blower housing is loose
Blower wheel out of balance, causing a vibration in the unit.

Open the unit and visually inspect the blower, blower housing, and listen for squeak. Be sure to shut off power until you get panels removed. Hope this helps!

Dec 08, 2013 | Air Conditioners

1 Answer

When the a/c is on it vibrates the whole house. Where is this problem coming from. It seems like it is in the squirrel cage, but i am not sure how to remove it

If the air handler is the suspected vibration point then pull the service panel off the air handler while it is running and look at the blower wheel while it is running. You should be able to see if there is a wobble in the blower wheel. If this is the case the blower wheel will need to be replaced and/or possibly the fan motor if the bearings are bad.
Since i do not know what brand unit you have i can't give exact instructions on how to remove the blower assembly. But as a general rule, there are only 4 or 6 screws holding the assembly in place. There are wires that have to be disconnected as well.
It is a pretty big job to replace a blower wheel or blower motor. In the case of a motor, the replacement motors are not original equipment and have to be modified to work correctly in any given system. This is better left to an expert.

Sep 02, 2011 | Air Conditioners

1 Answer

Whynter Portable Air Conditioner Model: ARC-14S. Problem: It sounded as if something fell inside the unit while it was operating (cooling) then it started to vibrate horribly. The vibration is only...

Hi,Whynter Portable Air Conditioner has many moving parts, and they all make noise and cause vibrations. Some of these parts are more likely to causing shaking and loud noises, and sometimes this signals a larger problem, something to watch and scrutinize. If serious enough, it calls for a repair.

Loose Parts

Loose parts cause the majority of shaking and vibration noises in your air conditioner. A few of the most common loose parts include the air compressor, the piston rods and even the fan or blower unit itself. These noises are clunking, clanking sounds that occur along with a vibrating action. The only method of repair is a complete compressor replacement, which is a repair only a certified air conditioner technician is qualified to make. The compressor is a fully sealed component, so individual parts in the compressor cannot be repaired.

Fan Blades

Fan blades cause noise, shaking and vibrations even when properly secured. If fan blades contact the exterior structure of the air conditioner due to a bent fan blade or broken and misaligned grate, a constant, repetitive noise and vibration results, which sounds like a ticking or banging from the interior of the air conditioner. Vibration in this case is limited but still present.

Mounting Brackets

When an air conditioner shakes, there is a problem with the mounting brackets. These brackets hold the air conditioner compressor steady as it operates. Normal vibrations and shaking would otherwise occur without these brackets. A loose mounting bracket causes the air conditioner to rock back and forth and creates a clanking sound. As the compressor starts up, this rocking and clanking sound begins, resulting in a very loud and fast vibration and noise. It also occurs when the unit shuts down.

Other Sounds and Vibrations

Sometimes air conditioners squeal, hiss, hum or screech. Each noise is often accompanied by a vibration. Humming sounds along with a vibration may indicate a bad capacitor, the electrical part responsible for starting the machine. Hissing sounds tend to indicate a pressure problem while screeching and squealing sounds are fairly common in window air conditioners and in central air conditioners. This sound is also a result of the compressor motor. It usually starts when the unit turns on and continues through its normal operating cycle. Vibrations always occur in the air conditioner due to moving parts and the compressor motor's operation.

Hope it helped..

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2 Answers

I have a carrier furnace and when my main blower starts up there is a short vibration just when the blower starts though and it doesn't seem to be getting any worse. the flame fires up ok and there doesn't...

I would remove both burner and blower compartment covers and reach into the blower housing and grip the center section of blower where it mounts to motor shaft. Try sliding the squirrel cage back and forth horzontally. If it slids much more than 1/8 inch then the motor bearing are probably just getting worn and allowing the motor tomake some extra noise when motor starts. If it has oil ports I would remove plugs and use 3-4 drops of machine oil and clean blower with brush and shop vac.
Other then that I don't think I'd worry much about it yet. Thank you and hope that helps.

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1 Answer

Weatherking heat pump sounds noisy but has a 20 degree air difference from intake to vents, is this normal?

Without hearing the "noise" it is difficult to diagnose via internet; however, I can tell you that the 20 degF temperature difference is a good sign.

If the noise is at the outdoor unit, try to determine if it is the casing or something else. Sometimes the casing can rattle and/or vibrate that can cause a sound. Sounds can also come from refrigerant lines rubbing against the casing. Other noise sources at the outdoor unit are the fan motor, fan blade assembly, and compressor. You can remove one of the fan motor wires from the contactor, tape off the end, and start up the unit for a few seconds to see if the noise is still present. Then you can replace the wire and remove the compressor wires from the contactor and repeat the test. This will help you determine where the sound is coming from.
If the sound is coming from your indoor unitl, the most common sources are loose tape, Blower wheel, blower motor, or blower housing. Also look for loose panels.

Without being onsite with toolbox in hand and being able to actually hear the sound, I hope you find this information to be helpful to you moving forward. :-)

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1 Answer

Furnace blower motor vibration

Check for a loose set screw on the motor shaft for the blower wheel.
Check the blower wheel for a missing balance weight.
Check the blower wheel for a dust buildup in the blades.
Check the blower wheel for a broken fin blade.
Check the blower motor shaft for excessive play.(more than 1/4 inch of play).
Check mounting screws on the blower housing.

Jan 04, 2010 | Ruud Air Conditioners

1 Answer

The ac unite has a lot vibration we just intall a new wheel blower

Wheel loose, out of balance (weight may of been knocked off during repair), loose/cracked mount/bolt(s). Take the motor/wheel assy. to where you got the wheel, they should check for balance.

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1 Answer

When turn on fan sounds like it need greasing and

If you are refering to the indoor blower, you need to shut off the ower to the unit, open the blower chamber and check the cleanliness, build up of dirt and debris in the squirrel cage can sometimes cause vibration. Check the "end play and see if there is considerable play in and out on the motor shaft, also check the mounting brackets to verify the intergity of the mechanical connections. If it is a belt drive, it could be the bearings, the bearing mounts or the cage itself if it is belt drive then consider changing the unit as it is well past time!

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1 Answer

York P3HU Gas Furnace Blower wheel makes noise and vibrates

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