Air Handler Blower Unit Repair FAQs

Air Handler Noise FAQs
Air Handler Runs Unexpectedly FAQs

Air Handler Blower Unit Runs Unexpectedly FAQs

Indoor air handler turns itself on for no reason.

My indoor air handler comes on all by itself. It runs and cools the house just fine but when I don't need the a/c on anymore I turn it "off".

It was "off" when the air handler came on and it just keeps running. I have to switch the a/c circuit breaker off and it stops. Any ideas? please help On 2012-12-11 by Tracy

Air handler keeps turning on & off

I'm looking for some help. My air handler keeps switching on and off while the A/C is turned on. The outside unit seems fine, although while the air handler turns off the pipe freezes.

This on and off situation occurs at random intervals. Sometimes it switches on and off several times a minute. Other times it may be 5 or so minutes prior to switching on or off. In either case I'm not reaching my desired temperature. Help - Anonymous.

Reply by (mod) -

Tracy and Anon

If HVAC equipment is turning on "by itself" - and you have made certain that your thermostat is not calling for the system to run here are some things to check

• AIR HANDLER / BLOWER UNIT FAN REPAIR FAQs - too SLOW, too FAST, other
• AIR HANDLER / BLOWER UNIT NOISE FAQs - fan makes squeaks or thumps or rattles, fan motor whines or buzzes
• AIR HANDLER / BLOWER UNIT REPAIR vs REPLACE FAQs

- make sure that the thermostat is set propertly to HEAT or COOL mode and then to be sure the TT should not call for the system to run,
In HEAT mode set the temperature to well below room temperature

or if you are in COOL mode set the thermostat temperature to well above room temperature = by 10 degrees or more

If the system runs anyway, check for

- thermostat wires that are shorted together anywhere in their run. A simple starting check is to just completely disconnect the thermostat wires AT THE HEATING OR COOLING APPLIANCE itself

- there is a bad control board or relay in the euqipment.

Keep in mind that in heating mode in very cold weather the system indoor air handler may run with backup heat operating and the outdoor compressor/condenser unit not running

 

When the temperature on the thermostat reaches 85-86 my blower will start by itself

When the temperature on the thermostat reaches 85-86 my blower will start by itself

Once this happens I am unable to start the compressor until the blower shuts off.

We have to turn on the air before it reaches 85-86 in order for the system to run properly. Any thoughts? On 2017-04-23 by Michael Adams

by (mod) re: blower turns on for no reason

Sounds like a bad control board or a wiring error.

Air Handler / Blower Fan Noise FAQs

Reader Q&A about buzzing, thumping, pounding, whining, squeaking or other noises from the air handler blower fan.

Roaring sound when my heat or A/C unit blower turns on

When my unit comes on (hear/air) it starts to make a roaring sound when u hear the blower kick in.

At first it sounded like something flapping, but now it sounds like the air flow is blocked. On 2018-01-25 by Mary

by (mod) - roariing sound at the furnace - turn off for safety

Mary

Watch out: I would turn off the air handler and call for repair.

My concern, knowing absolutely nothing about your heating system, is the risk of an electrical fire if an air filter has collapsed and been drawn into the blower assembly.

Rattling noise in attic air handler

I have a brand new Lennox A/C air handler installed. The handler located in the attic rattles: why? On 2019-09-14 by Rocco

by (mod) -

Roc

Rattles at the air handler unit can be as trivial as an inspection door not latched, loose hardware, loose duct connections, or as troublesome as a blower motor that's failing with bad bearings. You need to ask your service tech to take a closer look.

Tell us what you're told by the tech and we may be able to comment further.

Also either search InspectApedia.com (using the search box just above OR in the ARTICLE INDEX just above see HVAC NOISE DESCRIPTIONS for a complete diagnostic procedure for just about every noise type.

Wobbling blower fan noise - rattling sounds

When my air conditioner shuts off it makes a terrible noise. it sounds like the squirrel cage is rattling. what could cause this? - Anonymous

Reply:

Anon,

I'd ask for a check by the HVAC service company. If there is excess refigerant entering the compressor it can make a rattling noise and can destroy that expeensive component. If the problem is a loos fan itself that's easy to diagnose by checking the fan assembly with power off. The fan should not wobble.

How to repair a squeaking squirrel cage fan?

What do I do about a squeaking, squalling squirrel cage? It doesn't do it everytime the A/C comes on but more frequently than not. Not alot of room to see in there. WD-40? Any suggestions? On 2011-07-20 by Erma

by (mod) -

More about blower fans including squirrel cage fans is at BLOWER FAN OPERATION & TESTING

but to start, your fan may be repairable by tightening one or more allen screws that secure the fan cage assembly (or the bearings that carry the fan) to its housing through which passes the fan motor drive shaft.

With power OFF for safety, if the fan and all components appear to have no loose screws or mounts, but you can still wiggle the fan from side to side, then the bearings are worn and need replacement.

If your fan is pulley-driven, check also that the pulley is secure on the shaft and that the fan belt is not so loose as to be squeaking.

I would not use WD40 as it's not intended for a motor or bearing lubricant, though to be honest, I've sprayed it on almost every problem that has ever arisen at one time or another.

Better would be a lubricant intended for motors and motor shafts. Some blower fan assemblies use a grease fitting not oil.

Buzzing noise coming from the Return Air Handler

There is a buzzing noise coming from the Return Air Handler. I live in an apartment and they keep putting screws on the metal plate and the noise stops but then the buzzing returns later.

If I switch the unit off at the circuit breaker the noise stops. Do you think it may be the transformer or relay switch. Thank you (Sept 16, 2014) barbara holton

Reply:

Barbara

You're doing a better diagnostic job than your repair people. I agree that one should look for the buzzing component: often a failing low voltage transformer or a control relay.

Take a look at LOW VOLTAGE TRANSFORMER TEST for details.

Of course other vibration noises might be tracked to loose duct components or blower components, even an access panel. Those noises would also stop when the equipment is shut off.

Buzzing furnace blower runs only intermittently

Anonymous said:

Im having trouble here with my furnace blower. It runs intermittently. Then sometimes it slows down and stops after about 2-3 minutes or so then I hear the BUZZZZZ.

Yesterday I was sometimes successful kickstarting the wheel but later in the day found that this was more difficult to do. It has not seized and seems to only run when it wants to. I replaced the run capicitor and it fired up nicely - then after 5 min back to no fan and a buzzzzz again.

Getting VERY little heat from it. WOke up to 56 degree house today. HELP?

Reply:

Sounds as if there is a failing relay, a failing start capacitor (CAPACITORS for HARD STARTING MOTORS) and maybe ultimately a failed blower motor.

Watch out: if there are loose or arcing wires there may be also a fire hazard; I'd shut it down and call for heating service.

More buzzing sound diagnoses are at

• BUZZING SOUNDS & vibration sounds from A/C, heat pump or inverter or from other equipment in, or, or near buildings
• BUZZING NOISE DIAGNOSIS REPAIR - topic home

Air Handler Clicking Noise every 2 seconds

My central air is working but there is a clicking noise every 2 seconds and as I opened the door to inspect, I noticed a green led light blinking simultaneously with each click. Can you help? Is there a problem? - david waite

Reply by (mod) -

David,

The blinking light that you describe is almost certainly a diagnostic but I don't know what the specific light means for your system.

To decode a signal light one needs the brand and model of the equipment and with that information one obtains the service manual for the equipment.

The back of that manual will have a page or two listing the different blinking light signals and getting their meaning and telling you what needs to be done.

For example a blinking light might indicate that an air filter needs to be changed.

See

• CLICKING SOUNDS from air conditioner or heat pump system - also see FAN NOISES, HVAC - including ticking - also see HVAC TICKING NOISE DIAGNOSIS
• CYCLICAL REGULAR NOISES or vibrations

 

Cause of a whining / growling noise at air handler

Air handler can makes intermittent whining/growling noise. A/C is running fine. Might be trouble later, any sugestions? On 2018-09-24 by Leonard

by (mod) -

A good place to start in diagnosing this would be to look at the descriptions of the different kinds of noises and their possible causes, is found in HVAC systems.

This link is a good place to start.

• WHINING A/C compressor/condenser or blower fan motor noise

 

Air handler is whining and the fan won't run

Air handler whining.. No fan. On 2019-11-04 by Gina Muster -

by (mod)

Gina

Watch out: turn off power and call for repair - for safety. That sounds like an electric motor that can't start; we want to avoid an electrical burn-up or fire.

Diagnostic and repair advice are found

at ELECTRIC MOTOR DIAGNOSTIC GUIDE 

Air handler fan won't run; makes a loud thumping noise

My air handler fan starts to run but stops Makes a thumping noise and will not start On 2011-05-06 by John seward

by (mod) -

If this is a belt-drive unit check for a loose pulley broken belt, broken fan mount.

If this is a direct drive unit check for a bad fan bearing, motor bearing, fan mound.

Let us know what you find, it may help other readers.

see

• BANGING A/C or heat pump
• BANGING NOISE at AIR HANDLERS or in DUCT SYSTEMS

 

Pounding brick falling noise when AC shuts off on the roof unit

When our A/C roof unit shuts off there is a noise like a brick is being dropped on the roof.

Is this normal?

Had a barometric damper on previous house that did not make noise. George

Reply:

George:

Look for flexing ductwork or for a loose blower or component in the air handler.

If the noise is coming from a relay, compressor motor, fan motor, or other electrical component, shut off the system while waiting for repair.

Loud thumping sound after the a.c. turns off

My blower unit makes a loud thumping sound after the a.c. turns off. It sounds like something hitting against something. It sounds like air on a fan. Fan unitbwasvreplaced last year. Technicians can't find the problem. (July 24, 2014) H.Mulligan

Reply:

HM

Did you check for loose fan, bad fan bearing, or motor mounts that jiggle as the spinning components in the air handler slow down?

Strong air flow buckled air handler door - makes noises

Had a new ac unit installed and have great air flow that causes the air handler door to buckle and retract when blower starts and stops making an annoying sound. Any suggestions? (Sept 26, 2014) Don Brown said:

Reply:

Don it sounds as if there is inadequate return air ducting - the air handler is air-starved. I'd look into that problem rather than just stiffening the door. Just improving the door to stop the noise is treating the symptom not the problem.

Loud hissing scraping noises from the blower fan

My blower motor in air handler is making a loud hissing/scraping sound. What could that be? On 2016-06-19 by Ron con

by (mod) re:

Sounds like a worn blower bearing or a squirrel cage fan assembly that's come loose and is rubbing against something in the air handler;

If your blower is pulley driven, also check for a loose belt or pulley.

See

• HISSING SOUNDS, HVAC from A/C or heat pump system

Noisy blower on top of a block of units that never stops

What can one do in regards to a continuas very noisy large blower on top of a block of units, never stops! On 2016-06-09 by Karen odonnell

by (mod) re:

Review the system operation with an experienced HVAC tech to determine first if it's operating normally. Something as simple as loose parts can cause a horriffic noise.

 

Humming noise from air handler blower fan, fan won't run

Blower fan hums but does not kick on - On 2016-05-31 by Anonymous

by (mod)

Turn the system OFF for safety, then ask your heating or A/C service technician to check for a bad fan motor start capacitor or seized blower fan or motor.

See

• HUMMING sounds from A/C or Heat Pump system

 

Blower fan squirrel cage noise at end of fan on cycle

A/c in attic makes loud noises at end of cycle. Sounds like coming from squirrel cage off balance or bearing worn out and wobbles at end of rotation . happens at end of air flow and happens every 3 or 4 minutes. Noisy. On 2017-06-22 by Mike

by (Mod) re -

Mike: I'd look for a worn fan bearing and if the blower is operated by a motor and pulley system, also for a loose pulley or bad pulley bearing

Noises from the AC/Furnace sounds like a jackhammer

When our ac is running, the blower on our ac/furnace unit has started to make a lot of noise (sounds like a jackhammer) along with a burning rubber smell. I cut power to the unit and now would like to understand what has happened so I can repair it or probably get it repaired. On 2017-07-05 by Dale

by (mod) re:

Smart to turn off the power - before a fire got started.

Could be simply a loose component in the blower compartment or a jammed pulley or fan belt. Take a look in the blower compartment for something visually obvious and let me know what you see.

See

• BANGING A/C or heat pump
• BANGING NOISE at AIR HANDLERS or in DUCT SYSTEMS

Inter City HVAC BM1912GSPL4 blower noise - loose fan blades?

I have an Inter-city HVAC system installed when i built my home in 1995. Thee model (and mfr) number on the sticker is BM1912GSPL4.

my problem is, the blower fan (squirrel cage) began making noise a few days ago. i found a tutorial which duplicates the sound perfectly and is consistent with it's otherwise lack of symptoms. eg; no apparent vibration, good airflow, no squeals, chirps, stops and starts without issues, etc.

on the tutorial, the culprit is two loose blades on the squirrel cage. the tutorial suggests jbweld to repair the loose blade(s), or replace cage. i would like to replace it, but am unable to locate the part. sears says my model number is not in their database. any suggestions? james

Reply:

James,

I'd remove the assembly, take it to your local HVAC supplier, and see if they have a replacement.

Or check for a misread model number.

Keep me posted

Where is the noisy blower sound coming from ?

Somebody know, where is the noisy sound come from? Is coming from the cooled air blower? Or another equipments? I am really boring with its sound so much. I don't know how to fix this issue. please help me to fix it! (July 9, 2014) Chhayhour said:

Reply:

Chhayhour

You can find air conditioner or HVAC sound diagnosis procedures at

inspectapedia.com/noise_diagnosis/HVAC_Noise_Diagnosis.php