ECM Motor Troubleshooting — Part 3

In my last 2 posts, we discussed how to use your meters to check out ECM motors, modules, and control boards.  These checks involved taking voltage reading and resistance reading on the various components to see where the problem occurred that caused the motor not to run.

But, did you know that there are “diagnostic” tools out there that make this a lot easier?  Well, there are!

ECM motor controls can also be checked with the TECMate™ Service Tool.


The switch should be placed in the “ON” position and the LED light on the switch should illuminate when connected properly to 24 VAC. The motor should be observed for 15 seconds. The Table on the back of the TECMate PRO™ can be referred to for operation guidelines.

If the motor starts with the TECMate™ the system malfunction is not caused by an ECM module or motor problem.

1) When finished testing with the TECMate™, place the switch(s) in the “OFF” position on the TECMate™ and wait for the motor to completely stop. Depending on the program, sometimes the motor will not shut off immediately after a test; this is normal.

2) Once the motor comes to a complete stop, turn the system power off before removing the TECMate™. The 16-pin connector must be reconnected to the system before proceeding with the diagnosis. The connector is keyed and has one clip that should click when the connector is inserted properly.

3) The next step is to check the low voltage communication on the 16-pin connector as discussed in my last post. If control voltage is not present, the problem is most likely the communication from the control board or the communication through the 16-pin connector or harness.

The connections at both ends of the 16 pin connector and the wires to the connector should be evaluated for damage. The sockets must not be distorted, bent or pushed out of the connector.

If the motor does not start with the TECMate™, the electronic control (motor control) should be replaced. BUT — before replacing the electronic control module, test the motor to ensure it is not also damaged. Procedures for testing the motor are included in my previous post.

Final Installation Checks – ECM motors

A visual inspection of all wiring and connections, especially those removed while servicing should be completed.

The system should be setup as follows:

  •  The AC power should be reconnected to the HVAC system and verification that the new motor control module is working properly should be completed.  
  •  All leaks in return ducts and equipment cabinet should be plugged and sealed by approved methods. 
  •  Verify that the system is running quietly and smoothly, in all modes (heating, cooling, and continuous fan) and all stages (if applicable). 
  • The thermostat settings should be returned to the customers preference.

If this is a repeat failure, check the following:

  • Any evidence of moisture requires correcting the issue.
    • be sure there is an adequate drip loop in the wiring harness.
  • If the area is subject to high amounts of lightning strikes, the use of additional transient protection may be helpful.
  • If the unit is not already equipped with a “choke coil”, you may want to add this to the system (see older post on choke coils).

The nice thing about diagnosing with the TECMate™ is that it tells you right away if the motor/module is defective so you can concentrate on the harness / board side of your system if the motor runs.  If the motor does not run, it is probably a defective module but, you will still need to do the diagnostics in the previous post for the motor resistance checks before replacing  just the control module.  You may need to also replace the motor.

On most equipment today, the module and motor can be obtained as separate components.  Modules do need to be programmed for the specific manufacturer’s model and are not interchangeable either in the individual brand or across brands.  There is no universal program for ECM motors so be sure to get the correctly programmed module for your application.

I hope these last few posts have helped you in diagnosing ECM motors.  with the demand for higher efficiency equipment and components, ECM motors are becoming more common is HVAC systems and the need for proper diagnosis is becoming ever more a requirement for the technician working on the higher efficiency equipment.

About yorkcentraltechtalk

I have been in the HVAC industry most of my life. I worked 25 years for contractors on anything from residential to large commercial boilers and power burners. For the past 23+ years I had been employed by York International UPG Division ( a division of Johnson Controls) as a Technical support/Service Manager but I am now retired. One of my goals has always been to "educate" dealers and contractors. The reason for starting this blog was to share some knowledge, thoughts, ideas, etc with anyone who takes the time to read it. The contents of this blog are my own opinions, thoughts, experiences and should not be construed as those of Johnson Controls York UPG in any way. I hope you find this a help. I always welcome comments and suggestions for postings and will do my best to address any thoughts, questions, or topics you may want to hear about. Thanks for taking the time to read my postings! Mike Bishop
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11 Responses to ECM Motor Troubleshooting — Part 3

  1. John says:

    Just had a carrier infinity installed back in may dual stage with ecm. but it seemed to run on high all summer. Hope it works at low and high is there anything I can check verylittle knowledge I called carrier but they were no help

  2. Rose says:

    I have an ECM motor (GE 5SME44JG2001A) that is running but is making a racket of noise every time it kicks on. Can you give me some info on what the problem may be? The noise sounds like “clicking” noise. Quite loud.

    • ECM Motors do “rock back and forth” before they actually start. That would be normal. That should not cause a “racket” though.
      Could be something loose, blower wheel, etc.. If it is nothing obvious, then I would suggest you contact Regal Beloit, the motor manufacturer, at:
      Technical Team — Email: and see if they might give you some suggestions

  3. DAVID says:

    Is an ECM motor Ok if Y1 and W1 signals from T-stat energized at the same time (humidification mode)? Thanks

  4. Robert says:

    I have an Trane/American standard YCY042G1M0AD and the motor will not turn off. It was left on with no heat/cool at night then in the mourning it was running at high and will not turn off. The small fan CFM board with dip switches was changed out but it still runs and can only be turned of by breaker. The tech said it should have been the small (CNT03600) board since everything else he checked seemed OK. Would the check tool be able to tell if it is module or the other board? Thanks for any help in advance.

    • The TechMate will diagnose the motor, not the board. Specific check of the board would need to come from Trane since each manufacturer has its own programming. Voltage checks of the 16 pin plug would need to be done to see if it is sending power when it shouldn’t.

  5. Robert says:

    So What it seems is that the motor is ok if it is running and the techmate will not see a fault in the module. Since the Small (cnt03600) board is new then it is likely the BIG board (I think it is the IGN board) where the connections for the blower and inducers are. AC/Heat all work so I think I need to get a Tech that can figure it out. I don’t think he knows this type of system.

  6. Robert says:

    Called out another company and gave them all the details. They came out and could not figure it out. They called and talked to a tech and said it must be the Main Board (IGN). Now the Main Board (IGN) has been replaced and the fan continues to run. I did mention the Techmate and checking the 16 pins but he did not have one and did not check the individual wires. He called a tech (I believe from Trane) while working on it. When power is turned on the fan comes on at 1400 CFM. If heat is set to on, when it reaches temp the fan runs for quite some time then slows down and fluctuates speed but continues to run. When AC is on the fan does not change when temp is reached. Does anyone have a clue as to what might be going on here? Thanks for any help.

    • At this point I would suggest contacting the manufacturer of your furnace, ask for a dealer referral in your area who has the tools and understanding of your product. There are tools needed to properly diagnose an ECM motor and/or the control board. Without the correct tools and understanding, dealers become parts changers.

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