HVAC Blower Motor Constantly Running - ECM Module Home Repair

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[@Goliad_Respector]

Incredible. I can’t believe I hadn’t thought to solder the thermistor to the legs of the old one. Wow. Face palm. I’ve been having the same issue and I can’t figure out the slow fan speed and smooth rotation as though the motor is fine but it’s not getting enough current like if it had an external capacitor that was bad, but it’s an ECM so I couldn’t figure out what it was, it made no sense. The evaporator coils were clean, everything seemed fine. I was confused on how to properly test for the high and low voltage but it seemed like the issue was in the motor start up. I then heard of this issue with the thermistor but the foam covering made me think I couldn’t replace the thermistor? I just hadn’t thought of soldering the thermistor to the old legs. I cannot wait to try it. Thank you.

[@beachwave2]

Can the old thermistor be tested while attached to module ? Will it still give a good reading or does it have to be removed ? Thank you for the good video.

[@HowToDoitright]

Have to be removed

[@cjones8127]

I have a residential Carrier Performance series AC/HP with emergency heat strip with the Gentec ECM variable speed blower for our 3 BR house which was installed about 15 years ago. The A/C and heater functions all work fine it seems with the air handler blowing fast/high whenever there is a need for cooling or heating, but then the blower returns to a slowish "circulate" speed once complete. The problem is that this slow speed function of the fan which keeps a low volume of air just circulating, would not ever go off anymore. It used to go on and off depending on the need at various times, but now it runs 24-7. My therm is set to auto and the "circulate" feature is off. BTW, this slow speed I speak of is about 75% of the speed the low circulate speed is when I have it set to circulate, so I would say about 500 rpms. Well I thought for sure it was the A/C's main board had gone bad and replaced it with a new one, but nope, it was not the main board in the air handler. I made sure none of the wiring was shorted between the unit and the thermostat on the wall. I even removed the thermostat with all the wires disconnected and even then, the blower stays running as soon as power is restored. So could it be the ECM?, but how does it work normally all times except when it should go off? Sincerely, Baffled.

[@HowToDoitright]

Yes ECM is bad. You checked everything you could.

[@cjones8127]

@@HowToDoitright Thank you...I believe you are right, but the common sense part of me keeps whispering there is no way it can be completely bad and not fixable if it works fine during cooling or heating periods? Should I be shopping for just the module or the whole motor and would Am@zon be just fine for purchase? If I just replace the module, I will need to repack those shaft bearings I suppose after an approx total of 2,956,500,000 (3 billion)rounds over the last 15 years. Thanks again!

[@gioiann00]

My female friend is going to replace the ECM module by herself. Trying to make job as easy as possible for her. Does anyone know the correct socket size for removing the 2 bolts holding the ECM module?

[@soloch69]

Great video I just had a ECM motor kept on running wouldn’t stop at all even when I took off the green wire from the thermostat

[@HowToDoitright]

Yes that bad ecm

[@TrySkyLife]

@@HowToDoitright I have this same issue. Should I not order the thermistor? Fan is stuck on. Or should I order the modual?

[@DeepDiishh]

Thanks for the nice video and sharing your knowledge. Well done. Just to confirm, in this video, which shows the situation of your blower motor running at a slow speed...after you replaced the thermistor, and reinstalled the blower, did the blower motor indeed return to more or less a normal speed? ( my ECM blower motor is similarly running at a slow speed. I am contemplating what to do, maybe replace the thermistor. The motor windings ohm out okay. )

[@nicholasflores8783]

I went to a call yesterday that their indoor blower runs constantly. Fan set to auto, cool off, took off stat face, went to unit and fan still running. I took the g wire off the board terminal and fan still ran. I took the heat and cool spades off of the board and fan still ran. This leads me to think that the module and or motor is bad, does that make sense?

[@BrettGlass]

I had a new HVAC system installed last year and a honeywell stat that has 4 wire running to it.(no C wire). The system when in A/C mode will set there and run until I turn the stat up, but I have to turn it up 3 or 4 degrees or the temperature reading will jump a degree or 2 to match where I set it to. I know sounds crazy. It will also jump down and match within a degree or 2. SO... first I called honeywell thinking this must be a stat issue. They had me test the voltage readings of the 4 wires running to the stat. The 24v red was fine but one of the wires read lower like 9v and seemed to vary. Honeywell blamed the HVAC system as the problem. So I called the HVAC tech out and after thinking it was the wires running to the stat he checking the voltage readings at the unit with the stat wires removed, he got the same readings ( one circuit was low and varied) eliminating the wires to the stat as the issue. He then said it was an ECM module/motor.He did a warranty replacement of the ECM and said it's fixed. For some reason this issue takes a few hours before it acts up. Then the longer it runs the worse it gets. He finished the warranty repair and said even though the voltage is still low in one circuit the system was working fine, but the next day it did the same thing. I replaced the Honeywell stat again and it does the same thing also. Any ideas what I should do?

[@HowToDoitright]

I suggest turn off the AC. Turn off the breaker for both outside and inside unit and measure AC voltage on the low voltage wires. It’s possible your low voltage wire is not shielded and getting transient voltage. This can happen if low voltage wire run by someplace where you have high voltage wire running. This can also affect the readings. Also it could be your coil on the relay outside at the unit that picks up to run the compressor for the outside unit.

[@BrettGlass]

@@HowToDoitright Ok I'll try that. Got me thinking. If the issue is somewhere on the low voltage wire running to the outside unit and or coil on the relay, I could unhook those wire at the inside unit and see if that one low circuit voltage goes away. If it does I work toward the outside checking, if it doesn't then I would know it's not outside correct?

[@HowToDoitright]

@@BrettGlass yes that’s correct. Best way is to start with having the voltage and then one by one turn off breaker and check if it goes away with which breaker off. If it goes away with outside breaker off then you know it’s outside or vice-versa. Then you can trace it down by unplugging the wires and see which wire has the issue.

[@michaelprince5255]

What was the resistance on the bad thermistor?

[@HowToDoitright]

1M

[@iffgambetta5319]

Replacing the thermistor fix the problem of the fan running constantly?

[@HowToDoitright]

No it won’t. You will need to change the fan control module. I have one for sale if you want one.

[@TrySkyLife]

@@HowToDoitright do you have one for a 1/2hp genteq??

[@trackerse]

My air handler fan is running 24/7, I want to replace the thermistor on my ecm, my part number says NTC 1,0 1237, I can’t find this exact part number, can I replace with any part number as long as it’s a 1 oms thermistor ?

[@HowToDoitright]

Changing thermister may not solve your issue. Have you tested the old thermistor to be bad? I suggest look for a replacement controller without motor and replace the whole controller. If you email me your ecm model I may check if I have one.

[@trackerse]

The motor is a X13, there’s a silver label with WZDK370-312G1 White label HW19, 1/2hp 230vac

[@trackerse]

I changed the thermistor and it didn’t fix it

[@HowToDoitright]

Just like I suspected. Just order the control module

[@MrRerod]

After replacing the thermister, a year later the main blower motor (GE 1/2 hp 08/22/00 CNO2 011DH7) is making a intermittent high pitched whine (g#5 note) when on first stage. I "think" it's related to the module, but not sure. Anyone?

[@joesprauve2408]

Could be the bearings on it way out

[@maevamonrose]

my ecm 2.3 with 16 pins run all the time even when i disconnect the 16 pins wire. I replace the thermistor and no change. so I had to buy a 700$ motor to replace it

[@HowToDoitright]

Yes for that you could have just replace the module. Wasn’t any need to replace the entire motor. Just ecm control module would have been enough.