Goodman, Amana, Daikin GMVM96 error code b4
Blower motor current trip or lost rotor
Goodman is the platform name, and your unit may not say it
Amana AMVM96 / ACVM96, Daikin GMVM96 platform are the same board with a different badge, so this page covers all of them. The fault, the checks and the parts are identical, which is why there is one page rather than one per brand.
Quick answer
On Goodman GMVM96 (2010s), b4 is a fault. It means blower motor current trip or lost rotor. A first thing to check: Seized blower motor.
- Applies to
- Goodman GMVM96
- Goodman and Amana GMVM96, GMVM97, GCVM96 alphanumeric codes · Furnace · 2010s
- Type of code
- Fault
- Urgency: Needs attention soon
- First safe check
- Check the filter first. A fully blocked filter can overload the motor.
What b4 means on this model
The motor is drawing more current than the control allows, so the circuit has tripped. Often a seized motor, a failed capacitor, or a blower wheel that has bound against the cabinet. A motor that has been running and is now tripping was usually already going.
Symptoms you will notice
- Blower hums, buzzes or grinds without moving air
- Blower stops and restarts intermittently
- Furnace will not fire
- Code appears after the system has run for a while
Common causes
The code tells you what the control detected, not which part failed. These are the causes we see most often, roughly in order of likelihood:
- Seized blower motor
- Failed capacitor causing a rough start
- Blower wheel jammed against the cabinet or a blocked filter
- Motor winding failure
- Weak 24 volt power from a tired transformer
What you can safely check
These are homeowner-level checks. None of them need you to open a live electrical compartment or work on gas.
- Check the filter first. A fully blocked filter can overload the motor.
- With the power off, try turning the blower wheel by hand. Resistance or a gritty feel means the motor needs replacing.
- Look at the capacitor for bulging.
Do not do these
- ×Do not repeatedly reset. A motor that has tripped on overcurrent is being damaged each time it tries again.
- ×Do not run the blower with the cabinet access panel removed.
When to call a technician
Book a technician, do not keep resetting it
This fault will not clear on its own. Every power cycle gives the control one more failed attempt, and repeated attempts are what turn a cheap part replacement into a seized or contaminated system.
- This is a fuel-burning appliance, so treat anything involving a burner, gas valve or flue as technician work. If you smell gas at any point, leave the property and call the gas utility from outside rather than continuing to diagnose.
- If the appliance has stopped mid-cycle, is making a noise you have not heard before, or smells burnt, stop reading here and call. Those are symptoms of something the fault code does not describe well enough.
Filter and capacitor are fine. Motor replacement is not.
What it costs to fix
Parts
Motor $250 to $500. Capacitor $15 to $40. Filter $8 to $40.
Labor
Three to five hours on a gas furnace.
DIY or technician
Filter and capacitor are fine. Motor replacement is not.
Typical US part and labor ranges, 2026. They vary by region, model and contractor, so treat them as a planning figure, not a quote.
Scope of this code
- Code table
- Goodman and Amana GMVM96, GMVM97, GCVM96 alphanumeric codes
- Models in scope
- Goodman GMVM96, 2010s
- Checked
- Confirm on your own unit
- Find the model number on the data plate, then check this code in the service manual for that model. Manufacturers revise code tables between model years, and a revised board can renumber a fault.