Infinity Blower Diagnostic w/ Bert

In a Carrier Infinity system, the blower is in constant communication with the board. However, when the blower motor doesn’t communicate back, an error code shows up. In this case, we have an error code 44, which may point to a failed module or board.

Instead of replacing the module and using the process of elimination to diagnose the problem, you can use your meter to see how much voltage the board is actually sending to the module. In this case, Bert reads ~240v going into the blower motor. Then, Bert checks the control voltage and sees if there are 12 to 13 DC volts of power between the red wire and common at the blower plug; the readings are right on target. The reading between the common and yellow wire should be around 5 DC volts; Bert reads ~1.6 volts, so the board isn’t sending the proper communication voltage.

In the end, Bert would have replaced the wrong part if he had immediately replaced the module without testing it with a meter.