I used to be scared of service calls that had these motors 😱 This is for you if you are uncertain about how to troubleshoot and diagnose ECM motors. When I first started out in air conditioning ECM motors were so scary. I had no idea how to troubleshoot or diagnose them and I did not understand any of the wires going in or out of them. Needless to say, I had to learn and overcome my own fear, but it did take a while to fully understand how they worked. Let’s break it down to hopefully make it a little bit easier for you. The two basic things you will have to verify is, if your line voltage is present to the motor, and if your control voltage is present as well. Check the unit data tag, or the motor data tag to find out what the line voltage is supposed to be. Also verify what your control voltage is supposed to be. Depending on unit and make, some of them operate on 24 VAC and some of them operate on 0 to 10 VDC. If you have any questions, always refer to your equipment manual. Once you have confirmed that your line voltage is present move onto your control voltage. The benefit of an ECM motor is that it has different speeds for different modes, such as single stage cooling, two stage cooling, or heating mode and therefore consumes less energy. Ensure you find the common wire (for control voltage) and then test to the terminal for whichever stage you’re in. If it’s low speed for single stage cooling, test to that. If it’s high speed for second stage cooling, obviously test to that. If high voltage and control voltage are present, but your motor is not operating, it is very likely that your ECM motor has failed and needs to be replaced. Obviously also check for damaged wires or the motor being seized up mechanically and not turning at all. Hope this helped. If you’re tired of second-guessing your own diagnostic, you want to master troubleshooting and accelerate your career, join the HVAC Game Skool community. I’d love to see you there. Happy HVACing 🤙 #hvac #hvacservicetech #hvacapprentice #hvactroubleshooting #creatorsearchinsights - @thehvacgame