Air Handler Blower Fan Won't Stop - FAQs

Indoor AHU or Furnace Blower Fan that Will Not Stop

Air Handler Blower Fan Won't Stop Running FAQs

Air handler fan goes on and off even when the unit is off

My air handler fan goes on and off even when the unit is off. system works fine but when temp reaches setting on thermostat unit will turn off then fan will go on and off every couple of seconds.

The only way to stop the blower fan is shut breaker to our air handler. It's very strange. - by Andrew Biello

Reply by (mod) -

That sounds like a failed control, relay switch, or shorting wires. Or possibly shorted thermostat FAN-ON wires.

See the diagnostics

at BLOWER FAN CYCLES ON INTERMITTENTLY

Why does the furnace fan keep running even when the unit is turned OFF?

Why does my fan keep running when the unit is turned off. - by Dorothy Spencer

Reply by danjoefriedman (mod) - Why does my fan keep running when the unit is turned off

Dorothy

I think you're asking a question about a heating system not a more cooling system.

It's normal for the blower fan to run for a brief time at the end of the heat cycle to purge the remaining heat in the air handler. That avoids the risk of overheating and cracking the heat exchanger which would make heater unsafe.

If you search this website for the phrase

Blower fan continues to run after a call for heat

Then you will see the details

Comment by Rachel:

RE-posted by Mod without advertisement

Rachel said:

@Dorothy Spencer, It may be the clutch bearing in the air conditioner pump is worn out. This part has not been replaced. The air conditioning pump needs to be replaced.

Reply by (mod) - Why does my fan keep running when the unit is turned off

Thank you for the post, Rachel

Dorothy:

If you are asking about the cooling fan in the outdoor compressor/condenser unit for your air conditioner or heat pump, see the diagnostic suggestions

at FAN, COMPRESSOR / CONDENSER UNIT DIAGNOSE & REPAIR

If you're discussing the indoor air handler fan ,take a look at the diagnostic suggestions

at A/C or FURNACE FAN WONT STOP

Attic AC blower unit does not shut off

When my outside unit shuts off the attic unit continues to run and will not shut off, even after turning the whole system off the fan on the air handler unit in the attic continues to run, any ideas what this could be? Jodi

Reply: bad fan relay?

Jodi:

When you are "turning the whole system off" and the air handler fan continues to run

AND provided that no one has turne on a manual FAN ON switch at the thermostat or in the air handler such as on a fan limit control,

To be sure you're not manualy forcing the fan to run, see these diagnosis and repair articles:

• BLOWER FAN WONT STOP - LIMIT SWITCH
• BLOWER FAN WONT STOP - THERMOSTAT SWITCH
• FAN ON AUTO MAN THERMOSTAT SWITCH - settings
• FAN ON SWITCH ADDITION
• FURNACE or A/C BLOWER FAN WONT STOP - home

THEN if the fan isn't staying on for a normal reason among those in the articles just listed, I think that either there is an electrical wiring or a control board or fan relay control switch error (you'd need an electrician) or else you are not finding all of the blower fan control switches.

For example turning off power to the outside compressor/condenser unit does not turn off power to the indoor air handler unit.

In other words, if you actually turn off electrical power to the unit, for sure it has to stop running or there is a wiring or switch error. In that case switch off the circuit breaker.

Some fan controls include an always-on switch as do some thermostats. Check for those.

Jodi said:

Thanks for your input - it was a bad relay switch

Blower fan runs on continuously after set temp is reached on a heat pump system

I have a heat pump system. When the thermostat is in the heating position, the blower fan continues to run after the desired temp is reached and the outside heat pump unit stops.

The thermostat will continue to show heat1 in process after the heat pump has stopped and the temp has been reached.

When I reduce the temp on the thermostat the fan will stop.

I have removed the wire from the thermostat at the control board and the fan continues to run after the desired temp is reached and outside unit is off.

I have turned power off at the air handling unit for a reset and system will function as normal.

Later on will return to the same problem. I have a feeling the control board is not functioning as desired. Please help. Thanks On 2017-05-10 by Dan C

by (mod)

On a call for heat it's common for the blower fan to keep running until the thermostat is satisfied, then it should stop.

When the thermostat is satisfied but the fan won't stop, if you disconnect the thermostat wires completely right at the air handler (eliminating any question about a bad thermostat setting or shorted thermostat wires) the either there is a FAN ON switch set right at the furnace fan limit control, OR

Check to see of the backup heat is operating - suggesting that the outdoor heat pump unit isn't able to provide enough heat.

by Dan C aux heat doesn't work

The auxiliary heat does function.

by (mod)

I meant to suggest that if you continue to receive heat from the system and the blower fan is thus operating after the outside compressor condenser has turned off then you are probably running in backup heat mode.

In heat mode if the heat pump can't provide heat the backup or aux heat has to work, else you'll get no heat but the blower may run - depending on unit controls.

by Dan C re: get no heat after set temp is reached but fan runs on

I do not receive heat after the temp is reached that was set on the thermostat. The air coming out of the vents is not warm, but ambient temp air.

Heat pump as stated shuts down after thermostat temp is reached, but the fan continues to run with no heat coming out of vents.

by (mod) re: blower runs on after the thermostat is satisfied

Ok, I hope I've finally got it. The blower fan runs on after the thermostat is satisfied, blowing cooler air.

A brief heat extraction run-on is normal, typically a minute or less. Many minutes of running-on points to a bad fan limit switch control.

Air handler blower fan has trouble turning off

My air handler turns off but sounds as if it is struggling. The air flow isn't consistent. It is a Carrier installed in 2010. - Thanks, by Dave

Reply by (mod) - My air handler turns off but sounds as if it is struggling.

Dave,

What you describe could be caused by any of a number of problems, more than I can accurately guess with so little information. Your service tech will probably consider

Starting problems: a start capacitor for a motor that's having trouble starting or a bad controller relay

Stopping problems: a failing control board, relay switch, or possibly more subtle, a failing motor bearing

Blower fan won't stop - thermostat not even connected

Installing a rheem air handler. Attached wiring for thermostat. Without connecting the other ends to the actual thermostat and turning the power on at the unit, the fan comes on and will not shut off.

After thinking there was a short in the length of thermostat wire, so changed that, twice. Still comes on with the other end not attached to anything.

After playing around with it more, I took a length of single wire off a spool, attached it to the red wire in the air handler and nothing on the other end, disconnected the green and brown wire form the air handler, turned the power on to the air handler and the fan comes on.

If I take the length of wire off the red wire from the air handler and turn the power on, the fan does not turn on. It doesnt make any sense.

I even swapped out the circuit board to see if that was some how causing it, but it still did it. Does anyone have any ideas? On 2019-07-17 by Eric W

by (mod) - the fan comes on and will not shut off

Eric

Take a look at the debugging tips starting at FURNACE FAN WONT STOP https://inspectapedia.com/heat/Blower-Fan-Wont-Start.php

On a new installation I suspect shorted wires - just as you did.

When you disconnect the TT wires right at the air handler and the fan still insists on running then check for a FAN ON switch on the limit control (assuming this is heating & cooling air handler) and check any dip switches or jumpers on the fan control board.

On a new unit my last guess is a bad control board or fan relay.

The outside A/C unit cycles on and off though the inside fan will not stop

my fan is set on auto, and the inside fan will not cycle off. the outside unit cycles on and off though the inside fan will not. It use to. It is like someone set the thermostat fan to the on position. Even in the auto position the fan never turns off. The house is cool and everything else is fine. What would cause this? - On 2011-07-06 by Colleen -

Reply by (mod) - if your indoor air handler fan won't turn off rule out a thermostat switch

Colleen: if your indoor air handler fan won't turn off, either the thermostat is never being satisfied or someone has set a switch to run the fan continuously (or thermostat control wires shorting together are causing it to run)

In addition to the "fan on" switch on some thermostats, the fan limit switch found in the air handler of many systems includes a white button that can be set to make the fan run full time. Search InspectApedia for "fan limit switch" to find the article describing that device.

Follow-up by Colleen

Thank you, I will read the InspectApedia on "fan limit switch". We thought it might be the thermostat and replaced it twice. Replacing this did not change the fan staying on problem.

Reply by Mod:

To rule out the thermostat or its wires (that could be shorted together somewhere, causing the fan to run), disconnect the thermostat wires completely at their end at the air handler or control board.

Details are at FAN WONT STOP - THERMOSTAT SWITCH

Then if your air handler is also serving as a heating system be sure that the MAN-ON switch is not set ON there.

Those details are at FAN WONT STOP - LIMIT SWITCH

Then if the air handler keeps running when it should not there's a bad relay or control board or switch setting (found on some AHU control boards).

New split system indoor blower fan replaced, now it won't stop running

I have a Carrier split unit 2011year model heat pump. The blower stopped working on the indoor unit after a lightning storm.

I replaced the module for the motor which is the x13 model. The module has the capacitor and everything built into it.

After replacing just the module end of the motor the blower came right on and runs perfectly except now it will not shut off unless I open the breaker.

The control switch is in auto and the control is in off, yet fan continues to run.

I swapped thermostats with the downstairs unit and still have same problem.

I bought new relays and replaced and still have same problem. I then bought new thermostat wiring and still have the problem.

I also swapped out the control board with unit from downstairs and still have the continuous running blower.

The outside portion of the unit runs fine and cycles on and off by the temp like it should.

Is there anything else I can look at? ANY help would be greatly appreciated On 2017-06-07 by steve

by (mod)

Steve,

Best guess: this really sounds like a wiring error or a switch or control that you've left set to FAN ON.

Did you remember to check that there is no manual on switch on the fan limit control itself?

Detailed diagnostics are

at FURNACE FAN WONT STOP

by steve

i don't have any fan limit controls other than the thermostat. I know a lot of heat blowers have a timer or limit controller but as far as I know there is only the thermostat control for mine and even when set in of for heat or cool and auto for fan the fan still runs continuously

I have changed the thermostat and all other mentioned items and cant find anything that suggest another part to check. There is a constant 24v supply to the fan telling it to run.

by (mod) re: diagnose fan that stopped working after a lightning strike

Sounds like a stuck fan relay or shorted wires to the relay; I'd start by disconnecting the wires from the thermostat on the air handler end.

by steve

I will try disconnecting the wires from the thermostat at the fan side and see what happens tonight. Thanks again for all your input

I replaced the relays, thermostat, and thermostat wire, yet it still runs. That's why this has me stumped.

I even swapped out the control board. As far as I know these four things are all that it could be.
I do appreciate all your feedback Dan. Thank you for your advice and help

Keeprite furnace fan runs at high speed off and on at odd times independent of call for cooling or heating

Hi there,
I have a Keeprite variable speed furnace that seems to have developed a mind of its own.

The fan runs at high speed off and on all times of day and night without the call for cooling or heat. I tried disconnecting the thermostat, but the fan still cycles without it.

There are no error codes read from the flashing light on the circuit board. Do you have any suggestions? Any help is appreciated , THANKS! On 2018-09-06 by Ian

by (mod) - Diagnosing a Keeprite gas furnace fan that won't stop

Ian

Thanks for an important question about what we can almost call a ghost fan controller.

You did the first thing I'd suggest - disconnecting the thermostat wires at the thermostat.

The second step is to disconnect the thermostat wires at the air handler. If this shuts off the fan then the wires are shorted together somewhere.

The third step is to look at the fan controller card or relay in the air handler- more suggestions are in the article above.

AND as a last resort, let's find the model of your Keeprite gas furnace, then we can find the technical or service manual for it.

See KEEPRITE HVAC MANUALS for help finding the manual for your Keeprite furnace if you don't already have it.

Below is an excerpt from the Keeprite/ICP condensing gas furnace manual for the F/G 9MVE model

Adjust Continuous Fan Airflow/Low Speed Cooling Airflow

NOTE: When the furnace is used with a twospeed cooling or heat pump unit, the airflow selected for Continuous Fan via setup switch SW23, SW24 and SW25 will also be the airflow used for lowspeed cooling, and vice versa.

NOTE: When the furnace is used with a twospeed cooling or heat pump unit, adjust the Continuous Fan CFM setup switches SW23, SW24 and SW25 to match the airflow required for lowspeed cooling.

Select the required Continuous Fan airflow using setup switches SW23, SW24 and SW25 as shown in Figure 5 and Table 5

Heater fan won't stop after changing the air filter

My husband changed the filter in the heater and hit the emergency power off then turned it back on now the fan won't stop running any suggestions On 2017-12-26 by Angie

Reply by (mod) -

That sounds strange indeed.

It's possible that in the furnace he turned on a manual FAN ON switch on the fan limit control, or he might have set the fan to FAN ON at the thermostat.

Try turning the power off switch OFF again, Leave it off for a minute, then turn it back on.

If that makes no difference, check the settings of the FAN switch at your thermostat as well as checking the diagnostic suggestions in the article at FURNACE FAN WONT STOP

Why Won't the Furnace Fan Stop Running even when my furnace is OFF?

My furnace fan in my house won't turn off when my unit is off - On 2020-02-01 by Tab

Blower fan continuously running while heat off switches on heat and on auto no fire in the box fan still run - On 2019-11-15 by Jon tester

Sometimes my blower fan wont shut off for a while. It will work for half the day and then the other half of the day it will not shut off.If I flip the breaker off and right back on the fans stays off until the next cycle. - On 2019-12-28 by Jamie

My Coleman electric furnace will not shut off i have to use the breaker to shut it off - On 2020-12-04 1 by keith

I have a Payne all in 1 blower condenser unit. My blower is staying on all the time. - On 2020-07-13 by Spiro

Blower motor on air conditioner will not shut down. I put in a new control board,that didn't work.put in a new contactor switch.that worked for 8 day's then stopped working.put in another contactor switch .the same. fan motor still runs constantly. - On 2020-03-04 by Forrest

Reply by (mod) - What to check first if the blower fan won't stop in Heat or Cool mode

Jamie and others

First, always check your room thermostat. Has it been satisfied?

Cooling mode: That is, if in cooling mode the thermostat is calling for the cooling system to run until the room temperature drops to the set temperature on the thermostat.

Heating mode: Or in heating mode we have the same problem: the blower runs but the furnace or heater isn't bringing up the room temperature to the thermostat setting.

Is cool (in cooling mode) or warm (in heating mode) air being supplied at your air supply registers?

Other Things to Check

Check the thermostat settings to see if the fan switch is set to ON instead of AUTO

Check the fan limit control in your air handler/furnace to see if there is a manual FAN-ON switch that is pulled out to keep the fan running

Check for a defective fan limit control or fan relay control switch.

Check for shorted wires at a control board or at the thermostat.

Blower still not shutting off? Start by stepping through the Diagnostics given on the page above. Let me know what you find and then we'll go over what questions remain.

Why does the fan keep running even when the unit is turned OFF?

Why does my fan keep running when the unit is turned off. - On 2021-01-17 by Dorothy Spencer

Reply by danjoefriedman (mod) - Why does my fan keep running when the unit is turned off

Dorothy

I think you're asking a question about a heating system not a more cooling system. It's normal for the blower fan to run for a brief time at the end of the heat cycle to purge the remaining heat in the air handler. That avoids the risk of overheating and cracking the heat exchanger which would make heater unsafe.

If you search this website for the phrase

Blower fan continues to run after a call for heat

Then you will see the details

Comment by Rachel:

RE-posted by Mod without advertisement

Rachel said:

@Dorothy Spencer, It may be the clutch bearing in the air conditioner pump is worn out. This part has not been replaced. The air conditioning pump needs to be replaced.

Reply by (mod) - Why does my fan keep running when the unit is turned off

Thank you for the post, Rachel

Dorothy:

If you are asking about the cooling fan in the outdoor compressor/condenser unit for your air conditioner or heat pump, see the diagnostic suggestions

at FAN, COMPRESSOR / CONDENSER UNIT DIAGNOSE & REPAIR

If you're discussing the indoor air handler fan ,take a look at the diagnostic suggestions

at A/C or FURNACE FAN WONT STOP

Blower motor won't Stop: tech says motor and control board are bad

everything working fine today before the annual check up,the tech was leaving and finished but the motor kept on when I asked him if that was normal ,

no he said and after 22 minutes taking things apart and off and back on the tech said the reducer motor and control board are bad,

the only problem is he took the motor amp and blower motor reading and they were about the same as last years reading how can that be?

can you take the furnace blower motor amp reading if the motor and board is bad? On 2018-02-20 by Rick Mcgarr -

by (mod) - With a bad control board it's possible that the blower motor will not run.

Rick

Thanks for an excellent question. I'm answering from the precipitous edge of comptence - that is, I can only give a general reply.

With a bad control board it's possible that the blower motor will not run. In that case, to measure current draw (Amps) of the blower motor you'd have to disconnect it from the control board and hook up a temporary power supply to the motor. Then current could be measured.

By "Reducer" I think your tech is referring to a speed reducer for the air handler blower motor. I'm not familiar with a mechanical speed reducer on residential HVAC;

instead I expect to see a Variable Speed ECM Blower Motor where "ECM" refers to an Electronically Commutated Motor.

That's a more costly motor design that offers distinctive HVAC operating advantages such as quieter motor-operation, ability to fine-tune the motor output to varying conditions, improved humidity removal and more-comfortable air delivery speeds at greater HVAC system operating efficiency.

[ECM driven blowers are provided by Trane (Comfort-R) and Carrier (Infinity Control) and other manufacturers.]

I would never rush to replace the blower motor without some other careful tests.

Ask your tech if it makes sense to try replacing just the control board first or just the motor first.

Let me know what she advises.

Here are some control board test details adapted from suggestions described by highperformancehvac.com - you might ask your tech about this procedure:

Here is the order in which I'd do tests:

- check that power is on to the system

- check that there is no safety interlock switch keeping the blower off - such as the door safety interlock switch on the blower cabinet

- double check every single wire connection, including a check for wires that have pulled loose inside of a plastic connector plug
between the fan motor and the control board - I've found that problem myself more than once

- look for visual evidence of damage such as burns on the board

- if the motor starts slowly that may be normal for an ECM motor design - wait at least 7 minutes.

- check that nobody has bumped a dip switch on the control board, moving it out of the proper settings - compare the dip switch positions to the instructions for your HVAC unit

Notice that none of those steps - where most problems are found - are high-tech.

- confirm proper (24VAC) input voltage to the board

By noting the brand and model of your air handler as well as of the blower motor, if you don't have the service instructions for your equipment, download those from your manufacturer or poke around in our

MANUALS & PARTS GUIDES - HVAC where we have an avalanche of manuals for nearly every brand. Find the troubleshooting tips specific to your equipment.

Lennox G26q3-75-1. Fan blower won't stop

Have a Lennox G26q3-75-1. Fan blower won't stop, even after heat is reached, burner shuts off, and air temp cools.

Does not react to fan 'off' at thermostat, or even thermostat removed.

Replace fan limit switch as readings suggested - same result. Operates just like fan 'ON' at thermostat - no matter what. On 2019-01-13 by JMed -

by (mod) - what to do if the blower fan won't stop running

JM

But here's a tip: if the furnace blower fan won't stop even with the thermostat removed from the wall

I would look first for a fan limit switch (in the furnace) that is set to run the fan continuously

- see FAN ON AUTO MAN THERMOSTAT SWITCH

And also for similar advice you might need to

- see FAN WONT STOP - THERMOSTAT SWITCH

If that's not the problem - that is there is no switch actually asking the fan to run try disconnecting the thermostat wires at the furnace itself - shorted thermostat wires can cause the blower to run.

For a complete diagnostic procedure be sure to review the diagnostics

at FURNACE FAN WONT STOP

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-

Reply by mod

Greg:

First: check the settings at your thermostat using this article:

FAN ON AUTO MAN THERMOSTAT SWITCH

After that, 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.

Amana/Goodman ARUF Air Handler Blower just keeps going AFTER the thermostat is satisfied. Traced to clogged condensate drain.

I've got the same problem, as posted On 2020-03-04 by Forrest.

My Amana/Goodman ARUF3714C airhandler keeps blowing, even after thermostat reaches set-point; compressor shuts down, but airhandler keeps blowing. The problem is *intermittent*--sometimes airhandler shuts off, sometimes it just runs and runs (not the 65-second efficiency delay).

Figured it was the blower delay relay board; replaced it and all seemed ok for a few days. It started up again today. I called Goodman and a tech suggested the thermostat might be defective. I had a new-in-box thermostat on hand, and wired it in.

It's doing same thing--seemingly random failure of airhandler to shut down, after reaching set-point temp.

I'm wondering about either the control wiring, or the 24 volt transformer. We had a power outage a few days before this trouble started, and wonder if the transformer might have been zapped, and isn't putting out 24 VDC.

The other possibility is wiring--if there's some random short or open, responding to equipment vibration or...?

How to check the control wiring? Is "C"/blue the common ground? What wires should be 'shorted' to each other, or to ground, during different operating states? - \2020-07-10 by Steve -

Reply by (mod) - If blower keeps running check to see if the thermostat has been satisfied

Have you tried disconnecting the thermostat right at the air handler? That can rule the thermostat out.

Then before replacing any other parts, check each of the controls.

When the air handler keeps running, the most-common cause is that the room has not been cooled down to the thermostat's set temperature.

So let's check for causes of that trouble, such as refrigerant loss or a compressor that is shutting down.

Followup by Steve

I've already disconnected the thermostat, and replaced it with a brand new one...along with replacing the blower time delay relay board.

Reply by by (mod) -

I got that, Steve, but I'm not clear on whether or not you found that by disconnecting the TT right at the air handler was done at a time when the AHU was running when you think it should not.

Taking that step not only rules out a bad thermostat but also mistakes in thermostat wiring and also the more-subtle problem of thermostat wires that are shorted together somewhere enroute.

Followup by Steve (in GA)

thank you, I shall ohm out the control wires from thermostate mount plate, and check for shorts. Assumption: the W, Y and G should have no continuity
to C (ground), or to each other--correct?

I found a discussion in another forum with same symptoms (intermittent failure of airhandler to stop blowing after reaching setpoint temp), where poster found the G line was left 'floating' (as opposed to being grounded) at setpoint shutdown. He conjectured about putting a pull-down resistor across G and C, to bleed any stray/leftover voltage at setpoint shutdown. He mentioned a 5K.

I just installed a 100K across G and C. Should only load 24VAC transformer with an additional 24mA.

A cooling cycle just completed--system cooled to setpoint, thermostat clicked, and about a minute later, airhandler stopped blowing---good! Fingers crossed that this solved it!

Reply by by (mod) -

Right.

The simplest and most straightforward test is to disconnect a thermostat wires at both ends and then working from each end test for any continuity between any pair of them.

Let me know what you find

Followup by Steve (in GA) - Clogged condensate drain causes intermittent shut down of the A/C system

Well, it turned out to be something verrrrrrrrry simple, but somewhat elusive!

I checked all wiring from tstat to airhandler, and from airhandler to compressor. All lines were continuous, with no shorts to any other lines.

The compressor continued to run intermittently, with no icing seen on coils.

The vent temps were65-66 degrees.

After everything I tried (new airhandler fan delay/relay board, NOS tstat) got same intermittent results, I figured the compressor was shutting down for some type of overheat situation.

The reality...was different....*facepalm*

Contractor came out, gauged compressor and looked at boards on compressor.

He then checked the airhandler, and the condensate float switch (here it comes!).

He saw some water in the switch cup, and said "you've got a clogged drainline. That's what's shutting down the compressor." He blew out the line, and systems been running like a top since then.

The clog must have been *partial*, with slow drainage.

Between cycles, the line would drain enough to let float switch drop, and enable the compressor to run.

The compressor would run, cool the coils, and condensate would begin accumulating-- until it began to back up in the slow drain, and lift the float switch--and shut down the compressor.

I did actually peek in the float switch cup several times, and never saw anything. I must have been looking after it had drained down.

Genteq Endura ECM Blower Fan Runs Constantly - Why?

Thank you for all the very very helpful information found on this website! I am a new homeowner and I found the blower fan (Genteq Endura ECM FM19, 1/2 hp, 230VAC) installed has been running constantly. This is what I have gathered so far:

1. if I disconnect 5-pin low voltage signaling on the ECM, the fan still runs.

2. I checked voltage on the 4-pin power supply to the ECM, they are all correct (C-0V, L-115V, G-0V, N-115V).

3. snap-disc thermo switch checked.

4. heat sequencer checked (I have a heat pump and electric heat).

5. fan relay is quite hard to reach, but when I call fan-on, the relay clicks and the fan blows a little bit stronger.

6. interior of ECM looks great, no dust, no rust, no busted capacitor, perfect rubbery seal.

I suspect the ECM module is programed to run the motor non-stop, by the builder or previous owner? Program # 604253-05. Or what else could be the problem here? Thank you again!

Regards,
Nemo - On 2019-12-04 by Nemo -

Reply by (mod) -

I agree with you that typically there's either a switch set somewhere or a shorted wire or bad control

Is my HVAC blower problem a bad ECM?

Thank you for getting back to me. You mean you think it's the ECM problem (bad or set that way) as well?

What do I need to do, if I don't want the fan constant blowing? - On 2019-12-04 by Nemo -

Reply by (mod) - Check dip switches or jumpers on fan controller

First let's identify the exact brand and model of heater and then look at the manual to see what settings are available.

On most equipment there's actually a user operable switch that will turn the fan to run continuously. But on some it might be a dip switch or jumper.

The other place to look of course is at the thermostat. You can rule out the thermostat by disconnecting the thermostat wires entirely at the heater. If the fan keeps running then it's not a thermostat setting.

I had to replace the damper motor attached to the damper on my wood furnace. Subsequently, the fan motor would engage and not shut off

I had to replace the damper motor attached to the damper on my wood furnace. Subsequesntly, the fan motor would engage and not shut off when the plenum temperature dropped off below the limit setpoint.

At this point I replaced the limit control. Now wjen n operation, the fan limit will cycle the fan motor on for one minute and ten seconds and off for two minutes fifteen seconds.

I will do this wether the thermostat is calling for heat or not until the fire burns out.

It is part of a wood oil combination, two furnaces using the oil furnace fan motor, Each has itès own fan limiy conntrol, the oil side works fine. Is it possiblt the coil or relay associated with the wood fan limit is weak and causing the limit to engage (Dec 31, 2014) Dan

My furnace fan keeps blowing after the thermostat temp is satisfied. If I remove the thermostat then it will turn off after a few minutes or if I turn off main power it will stop and reset after I turn power back on. This doesn't happen all the time. I replaced the fan control board but no help.

Reading the description above about under the header Primary Limit Control, Goodman Furnace ... 3 The circulator blower to remain energized continuously until limit control resets. is confusing. So I'm not sure what my issue is here. (Feb 13, 2015) digitthead

Reply:

Dan and Digithead:

This sounds like a wiring error, a damaged limit switch, or odd cycling plenum temperature on the furnace.

Detailed diagnostics are at FURNACE FAN WONT STOP

My mobile home furnace blower is not shutting off

The furnace blower in my (Park Model) mobile home periodically fails to shut off after reaching desired temperature. (Jan 14, 2015) Scott said:

Reply:

Scott

In the More Reading ARTICLE INDEX links see the diagnostics at

• FAN WONT STOP - LIMIT SWITCH
• FAN WONT STOP - THERMOSTAT SWITCH

Service tech left a wire connected wrong - fan won't turn off

A wire was in the wrong place...lol...its fixed...ignore my look for help.

I just had my furnace rewired because the wires were all dry and damaged and now the fan won't turn off?

It is set to Auto on both thermostat and on furnace but can't figure out why it won't quit running. I put cover back on and waited 15 minutes and turned switch and power off from breaker to reboot?

I had a heating specialist come in a couple months ago and he completely missed the burnt out wires running to the motor and today I had them all rewired, and now the motor runs, but won't quit. On 2013-03-11 by Bridget

Reply by (mod) -

Bridget, thank you for the problem report - it will certainly help other readers.

Your note illustrates an important aid in debugging a heating system problem: ask the question when did the symptom first appear? What changed or what was done around that time? Often the two are related.

 

What to do if the split system blower fan won't stop

Have a split system..set temp at 68 and after getting to desired temp the fan keeps running ....the temp went from 68-76 in a hour. (Feb 26, 2014) Charles McMillan

Reply:

Charles,
Because the temperature has exceeded the thermostat setting there's clearly a problem.
I'd start by eliminating the thermostat itself from the equation.

Just disconnect the thermostat wires - if you disconnect at the thermostat (be sure to notice color codes and connection points) then IF the heat keeps running, then

Next disconnect the thermostat wires at their other end - at the heater controller

Then if the heat keeps running the problem is at the heater controller not in the thermostat and its wiring.

Try turning off all power to the heating system; wait five minutes. Then turn power on and see if it behaves properly.

If not it's time to call for service.

You can also search InspectApedia for "HEAT WON"T TURN OFF" to see our diagnostic suggestions.

Or see

• BLOWER FAN WONT STOP - LIMIT SWITCH
• BLOWER FAN WONT STOP - THERMOSTAT SWITCH

Troubleshoot intermittent, long Blower-ON intervals for Thermo Pride Furnace

What causes a thermo pride furnace blower to run for long intervals 35", then off for 30 sec. then run again. When NOT calling for furnace heat coverage. the blower fan limit changed 3 times. Anon

Reply:

Anon:

Is just the blower running or is the burner on the furnace also running?

In any event, look for a wiring error, wires shorted together, or a bad thermostat or control board.

Detailed diagnostics are at FURNACE FAN CYCLES AFTER HEAT

Air Handler Blower Won't Stop - Cooling Mode, FAQs

The Q&A on this topic can now be found

at FURNACE or AC BLOWER FAN WONT STOP in COOLING MODE FAQs

Air Handler Blower Won't Stop - Heating Mode, FAQs

The Q&A on this topic can now be found

at FURNACE or AC BLOWER FAN WONT STOP in HEATING MODE FAQs

Other Air Handler Blower Won't Stop FAQs

The Q&A on this topic can now be found

at FURNACE or AC BLOWER FAN WONT STOP - OTHER FAQs