b3 Blower motor limiting (power, temperature or speed)

What the control is telling you

The motor is running in a limit mode. The furnace runs, but airflow is lower than it should be.

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

Likely causes

• Dirty filter
• Restricted ductwork
• Undersized ductwork
• High ambient temperature around the furnace

Test and repair steps

1. Check and clean or replace the filter.
2. Check ducts for blockage and open all registers.
3. If ducts are undersized for the system, they need to be resized.
4. 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

• 88 Power-up self check
• b0 Blower motor not running
• b1 Lost communication with blower motor
• b2 Blower motor size does not match model data
• b4 Blower motor trip (lost rotor control or high current)
• b5 Blower motor locked rotor
• b6 Blower motor over/under voltage or over temperature
• b7 Blower motor missing parameters