GE ECM Blower motor problems

The following is my encounter with a GE (aka Regal Beloit) ECM motor used in a Trane Air Conditioner. This Air conditioner is a little over 5 years old and I am already on my second problem. For the first problem I had called an HVAC technician out. He replaced one capacitor and one wire and charged me $640 for about an hours work. When my unit failed a second time I decided not to call a technician but to try and fix it myself.

The problem was simple, no air coming out of the air handler. After going through numerous tests that I found on the internet I disconnected the ECM module from the ECM motor and ohm-ed out the 3 wires going to the motor. The 3 wires to ground had high resistance. This was good. Ohm-ing the three wires to each other showed an imbalance. 2 combination of wires showed 4.1 ohms and the last pair showed 1.5 ohms. This indicated that the 3 phase motor had failed. So I purchased a new motor and this fixed the problem.

I was curious to find out why the motor failed so I took it apart. The motor label is shown in the first image below. This was Manufactured by GE motors which is now owned by Regal Beloit. The second image shows the top of the motor with the lid removed. It is difficult to see in the second image but at the very bottom of the photo are 2 wires that cross. These are from 2 different phases and you can see a burnt spot where they have shorted together. This is more clear in the 3rd image at the left side of the image.

As an Electrical Engineer it was clear to me what happened is that these 2 wires, after over 5 years in a high vibration environment (HVAC system), rubbed against each other and over time the enamel coating rubbed off causing the two wires to short. There is no other word for this other then poor engineering on behalf or GE/Regal Beloit. After writing to them their only response was that they follow industry standards.

bruce.forsberg@gmail.com