FAQs on repairing Indoor air handler or blower unit for A/C or heat pump or furnace systems, set #2:

More Q&A on AHU or air handler unit / blower unit troubleshooting and repairs.

This article series explains how to inspect & repair the indoor components of air conditioners and heat pumps: the air conditioning system indoor air handler units, blower units, or AHU's, (also called fan coil units) including the air conditioner blower fan, the indoor cooling coil or "evaporator coil", air conditioning system filters, and the causes, cures, and prevention of air handler leaks that lead to rust, damage, and mold contamination in the air conditioning system.

Air Handler / Blower Unit Diagnostic FAQs 3

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These questions & answers were posted originally

at AIR HANDLER / BLOWER UNITS - home or at BLOWER FAN OPERATION & TESTING- home. Be sure to see the diagnostic and repair advice that begins in either of those articles.

The air handler page is the more-broad topic addressing all components of the air conditioner or heating furnace air handler while the blower fan page focuses on the fan itself and its direct controls.

Article Contents

• AIR HANDLER / BLOWER UNIT FAQS
  • AIR HANDLER / BLOWER UNIT FAN REPAIR FAQs - too slow, too fast, other
  • AIR HANDLER / BLOWER UNIT REPAIR vs REPLACE FAQs - replace the evaporator coil, replace the whole unit?
  • AIR HANDLER / BLOWER UNIT WON'T START FAQs - or won't keep running
  • AIR HANDLER / BLOWER UNIT WON'T STOP FAQs  - also see FURNACE or AC BLOWER FAN WONT STOP FAQs
  • OTHER AHU BLOWER FAQs - below on this page, consolidation in process
  
  

Furnace Draft Inducer Fan Won't Run

I have a Carrier single stage furnace that at start up the inducer motor doesn’t run but the fan blower does On 2017-11-21 by Jerry

by (mod) - heating systems that requires a draft inducer fan

Jerry,

Watch out: for safety, heating systems that requires a draft inducer fan should be wired such that if the draft inducer doesn't run the burner will never turn on.

Because without the proper draft the system could be unsafe.

If that's your situation then it sounds as if you need help from a heating service tech to find out why your draft inducer doesn't run.

Undersized air ducts caused our heat pump motor to burn out?

No air was blowing from our heat pump. Techician said the motor was burned out and we need a new motor. He said it probably happened because when they put the new heat pump in 2 years ago they didn't put new air ducts in, so our old ones are probably too small and made the motor burn out. Could this be true? On 2017-09-13 by Kay

by (mod) -

Kay

I am not smarter than your onsite technician. But I suppose the tech thinks the motor for your air handler blower was over-worked.

On the face of it I'm surprised that a new heat pump would require new air ducts unless you were completely redesigning the system and its capacity.

Keep in mind that some techs can be smart at HVAC equipment repair but not good at communicating clearly.

Blower motor speed will not change.

Blower motor speed will not change. I have a freeze-up issue with the A/C not that the refrig has been replaced. The filter and evap are clean so I believe I'm not pushing enough air thru the evap. In testing my blower motor it seems that no matter how I wire it, it runs at the same speed (3-phase, 4-sped options).

I checked the resistance of each winding and they read in appropriate steps - but my ear tells me the blower is running at the same speed on the low setting as it is on the high. Any ideas what would cause that? On 2017-08-30 by Skip

by (mod) -

The motor may be a single speed machine. Did you check the data tag?

Low refrigerant can also cause coil icing.

Condenser unit won't run after I cleaned off wet leaves

I took the top off my central air unit to wipe the wet leaves, & dirt out i put the top back on

i tried to be careful & now it has power but fan doesnt turn did i maybe bump a wire plz help me its so hot i dont h $ right now is there a reset button On 2017-06-13 by Anonymous

by (mod) - bumped a plug-type wiring connector and loosened it.

Anon

Most-likely you bumped a plug-type wiring connector and loosened it.

With power OFF to the unit, you can remove the cover and look for wires to the fan motor - follow those to see if there's a disconnection.

Assuming that the fan and condenser/compressor unit was working last time it was used, and that you had power off to do your cleanup, it's not likely that there is a fan reset button problem; the reset on a fan motor trips if a motor overheats; not all fans have such a button as some thermal overload resets are internal and will re-set themselves automagically after the motor cools down.

Blower won't start but diagnostic lights say it's running

Have a blower motor that won't start.

1) Ran 120 VAC to connections on motor, motor spins up fine.

2) Pulled the controller board, thinking that this must be the problem, after looking at the Board diags, wasn't sure and put it back.

3) After installing the controller board, 2 slow blinking lights which diags say indicates it is on. (Motor still won't start)

4) Checked Drain Pan - Empty, checked the line, no blockage.

5) Cleaned Filter

Not sure where to go from here.

Any thoughts?

Thanks On 2017-06-12 by George

by (mod) -

George,

Also check for a bad door safety interlock switch on the access compartment door to the blower.

New thermostat in my house now my blower motor won't shut off

I just put a new thermostat in my house now my blower motor won't shut off any ideas? On 2017-06-06 by Greg-

by (mod)

Greg:

I can but suggest double-checking the thermostat wire connections, as I'm guessing nothing else changed and that the blower was working before the change.

Where is the blower fan reset button on my heat pump?

No blower fan reset button on my heatpump. How so I reset it? On 2017-05-27 by percy

by (mod) - No blower fan reset button on my heatpump

IF the motor has an internal thermal overload protection it will self-reset after the motor has cooled down. Leave power off for 15 minutes or longer.

If the motor has voltage delivered at its terminals and doesn't run after that, the motor is shot and needs replacement.

Pulley fell off in Westinghouse blower unit - can't get it back on

I have an old (1965) Luxaire furnace with a Westinghouse blower. There was a terrible noise yesterday, I found the large pulley had fallen off. We couldn't get it back on.

Looks like the threading is stripped. Ordered a new pulley from Grainger. There is no threading on theirs. Grainger said, that is how they are now. I can get it lined up but it won't go on past the first thread. Any tips or ideas? I am alone with a 4 year old & it's chilly! On 2017-02-21 by Stacey

by (mod) -

Stacey

Usually a pulley is pushed onto the motor shaft and is secured with an allen screw or set screw. But if the pulley you ordered won't slip onto the shaft where it belongs one would need to replace the shaft, motor, or blower parts. YOu could try filing the shaft but I worry that if the pulley is askew the system will stress the motor or blower and lead to a new failure.

Should there be some travel on the shaft of the blower motor?

Should there be some travel on the shaft of the blower motor? On 2016-12-27 by T-bone

by (mod) - end play when moving the blower motor drive shaft

Good question T

A bit of end play when moving the blower motor drive shaft in and out of the motor - that is, along the long-axis of the shaft - is usually OK but if there is lateral p lay - you can wiggle the drive shaft from side to side in the motor, then the bearing(s) is (are) shot.

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Continue reading at BLOWER FAN OPERATION & TESTING - home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see AIR HANDLER / BLOWER UNIT FAQs-4 - more-recent questions and answers about air handler units AHUs Blower Units Fan Units

Or see these

Recommended Articles

• BLOWER FAN OPERATION & TESTING
  • BLOWER FAN CONTINUOUS OPERATION
  • BLOWER DOOR SAFETY SWITCH
  • FURNACE BLOWS COLD AIR
  • FURNACE FAN CYCLES AFTER HEAT
  • FURNACE FAN CYCLES DURING HEAT
  • FURNACE FAN STOPS EARLY
  • FURNACE FAN WONT START
  • FURNACE FAN WONT STOP
  • WOOD FURNACE FAN LIMIT CONTROL
  • CAD CELL RELAY SWITCH

Suggested citation for this web page

AIR HANDLER / BLOWER UNIT FAQs-3 at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

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