b6 Blower motor over/under voltage or over temperature

What the control is telling you

The blower motor shut down because line voltage was too high or too low, or its power module got too hot. Furnace will not run. ComfortNet thermostat shows MOTOR VOLTS b6.

Applies to: GMVC95/AMVC95 upflow and *CVC9 counterflow two-stage furnaces

Likely causes

• High line voltage
• Low line voltage
• High ambient temperature

Test and repair steps

1. Safety live voltage checks only with proper PPE.
2. Measure line voltage at the furnace. It must be within the range on the rating plate.
3. Check the furnace location is not too hot.

Settings for these units

• Normal status displays (7-segment) · Goodman/Amana GM9S96/AM9S96
• Normal status displays (7-segment) · Goodman/Amana GM9S80/AM9S80
• Normal status displays (7-segment) · Goodman/Amana GM9C96/AM9C96
• Minimum recommended filter size · Goodman/Amana GM9C96/AM9C96

Models that show this code

10 models in Goodman/Amana *MVC95/*CVC9 two-stage ComfortNet

Other codes on the same units

• b2 Blower motor size does not match model data
• b3 Blower motor limiting (power, temperature or speed)
• b4 Blower motor trip (lost rotor control or high current)
• b5 Blower motor locked rotor
• b7 Blower motor missing parameters
• b9 Low indoor airflow
• C1 Low-stage cooling
• C2 High-stage cooling