Fan coil or furnace ECM motor repair process from diagnosing the problem to part identification and replacement along with other helpful tips.
What is an ECM motor you ask? Many residential furnaces & fan coils these days use this "electronically commutated motor" technology to run the blower fan.

These ECM motors are commonly called brushless DC (direct current) motors, but unlike the inexpensive, tried and true PSC (permanent split capacitor) motors that run directly on residential single phase AC (alternating current) and have been used in the HVAC industry for decades with little issue; these new residential ECM motors use an expensive and failure prone electronic control unit. The brushless ECM motors themselves are robust and can last for decades, the problem & main failure mechanism is the ECM control unit itself.

The ECM controller is usually bolted to the back end of the motor and can be replaced independent of the motor. The ECM is controlled by an internal micro controller, and uses what is commonly known as a 3 phase inverter bridge, which uses 6 FET/IGBT transistors that switch on and off very rapidly and are precisely timed to create a 3 phase AC waveform to drive the motor. Motor position for proper phase timing is done by back EMF sensing. In essence, the motor is actually a 3 phase AC motor with precise adjustability as the 3 phase waveforms can be altered based on the control algorithm.

The benefit with ECM technology in residential HVAC applications comes in the way of precise motor speed and torque control; thus has energy savings & air flow benefits over a fixed or multispeed PSC motor (totally application & usage dependent of course). They also provide soft start and soft shutdown which prevents current & voltage spikes/sags on your electrical system as well as extending motor life.

The problem with ECM controllers is they fail often, don't like dirty power at all, have many different part numbers due to the many different model specific protocols, and can cost an arm and leg to replace.

By definition, they represent a false economy as the marginal energy savings ECM motors can give, are often offset by an order of magnitude from service call & component replacement repair costs, not to mention manufacturing costs along with customer down time waiting for specific ECMs to be ordered in. Service repair bills of over $1K USD are not uncommon! Parts costs alone are usually $400 and up.

Below are links to ECM 3.0 parts shown in the video & the Genteq Service Guide link (free PDF download).

ECM 3.0 Modules...
HK44EA123: http://amzn.to/2peUiek
HK46EA123: http://amzn.to/2q91iyc
HK52EA123: http://amzn.to/2pPUxhH

Motor & ECM 3.0 Combo...
58MV660001: http://amzn.to/2qKi7wm
58MV660004: http://amzn.to/2qKi97s
58MV660002: http://amzn.to/2pPSOJn
58MV660003: http://amzn.to/2q94V7r
58MV660005: http://amzn.to/2pPVab3

Genteq Service Guide:
https://www.thedealertoolbox.com/cust...

Video Chapter Time Index:
Intro 0:00
Demoing the motor problem 1:12
Reading the DTC (diagnostic trouble code) 1:46
Removing the fan assembly 2:33
Removing the ECM from the back of the fan motor 4:18
Testing the motor for opens & shorts 5:47
A look inside the ECM & basic operation discussion 7:14
Looking for replacement part numbers to order correct ECM 12:38
Used ECM 3.0 arrives & discussion 17:10
Installing the ECM 3.0 to the motor 22:26
Reinstalling the fan assembly 24:05
Confirming the new used ECM 3.0 works & conclusion 25:09

DISCLAIMER: This video is for information and entertainment purposes only. It's no substitute for prior mechanical/electrical/HVAC experience and/or training. You work on your HVAC system at your own risk.
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