In a previous post , I explained what an X-13 (constant torque) motor is and how they operate. Now that you understand what it is, now we can discuss how to properly troubleshoot the X-13 motor.
Before troubleshooting any HVAC system, it’s a good practice to become familiar with the components and wiring diagram, check for and follow any on board diagnostics (fault codes in the manufacturer’s control board). On X13 motor systems (as with any blower) it’s also a good practice to check the tap (speed) selections and delay (both on delay, if available, and off delay) settings on the control board. The unit’s manuals will typically be required for these settings and can also provide valuable sequence of operation and troubleshooting help. (When all else fails, read the instructions).
If the motor is running but the system is noisy, shutting down on its limits or safeties or the evaporator coil is freezing, there is a good chance the motor is good. The problem is most likely external to the motor.
-Check the tap selections using the manufacturer’s guide for cfm vs. static pressure (proper air flow).
-Check the air distribution system components for dirty components and closed dampers, registers and grilles.
-Check the system static pressure and make repair(s) if it is above the manufacturer’s recommended maximum level.
If the motor is not running, the following checks will diagnose whether it is a good or bad motor. Always disconnect the power to the HVAC system before disconnecting or reconnecting any connectors to these motors.
There are two inputs needed to operate this motor, (1) a high voltage constant power source, and (2) the communication that selects the torque value (cfm) in each tap per demand.
–Checking the High voltage input : First check the high voltage to terminals (L) and (N). There should be 115vac or 230vac, depending on the model, between these two terminals whenever there is power to the system, regardless of a demand call. Applying incorrect high voltage to the X13 motor may cause the motor to not operate, or even damage the motor. On 115vac systems, make sure the polarity or the power connected to the motor is correct. If this voltage is missing, fix the problem in the system and try to run the motor. If the voltage is within ± 10% of these ratings then move on to the next step. If the voltage is above or below the ± 10% of these ratings, fix the voltage problem first, and try to run the motor. Proper grounding should always be checked and repaired if needed.
Also, if you read my post on X-13 motors in 3-phase systems, both power legs to the X-13 motor must be the same. You cannot use the “wild or stinger” leg on a 3 phase system.
Checking the communication input
The following information must be known before troubleshooting the low voltage communication to this motor.
- Which tap(s) have been programmed and what are their purposes (heating airflow, cooling airflow, continuous fan airflow). In other word, which is High, med high, med low, low-speed in relation to the positions on the motor. Keep in mind, even though the motor has 5 possible inputs, with some applications, all of the taps may not be programmed. Use the manufacturer’s wiring diagram or sequence of operation to see what taps are used and programmed.
- Where on the manufacturer’s controls or circuit board does the low voltage communication come from by demand or mode?
- The sequence of operation of the manufacturer’s controls or circuit board (where the low voltage communication is sent from the unit control to the motor from each thermostat demand and if there are any delays).
If no low voltage communication (typically 24vac) is measured at the motor on taps 1-5, check the HVAC system wiring, controls and demand call. Always check low voltage between terminals 1-5 and (C) at the motor, never ground. Once the problem is corrected, confirm that the low voltage communication is applied to a programmed tap. If proper low voltage communication is present at a programmed tap, with proper high voltage to the motor and it still does not operate, the motor is failed. A direct replacement motor from the manufacturer for the same model and size unit is required. X-13 motors, like full ECM motors have a factory program in them for the specific model. You need to make sure you replace an X-13 motor with the correctly programmed motor.
If all the taps are programmed, you can try moving the 24 volt input from one tap to another to see if the motor will operate.
As mentioned above, if you do find a failed motor, you need to replace it with a correctly programmed one.
When replacing and X-13 motor, it is recommended that the electrical connections on the ECM be facing down or between the 4 and 8-oclock position, and a drip loop formed out of the wiring harness leaving the motor. This is to prevent any moisture or water that may get into the motor area from running into the connectors where it could cause damage to the control. Also, the X13 motor should be mounted so that the belly band does not cover any of the motor vents, and is not located in the “Keep Out Area” approximately 2.75” from the control end of the motor.
In most systems, the manufacturer will install the motor in the correct position and provide the drip loop. However, keep in mind when multi-position systems are installed in a position other than the way the manufacturer constructed it, the motor may need to be turned and the drip loop re-arranged.
One last thing to remember, with all ECM and X-13 motors, the variable speed ECM may rock back and forth when it first turns on. This is normal operation for the control to figure out the proper direction to operate the motor.
Hopefully, this post will help you diagnose the standard ECM X-13 motor.