HVAC Error Code A6 — What It Means & How to Fix It

What Does This Error Mean?

Error code A6 on most HVAC systems means the indoor (evaporator) fan motor has a fault. The indoor fan is what circulates air over the evaporator coil and blows cooled or heated air into your living space. When the system detects that this fan is not spinning at the correct speed — or not spinning at all — it shuts down and shows A6 to prevent coil damage and overheating.

Affected Models

Mini-split air conditioners
Central air handlers
Heat pumps
Ductless HVAC systems
Ceiling cassette units

Common Causes

The indoor fan motor has worn out or burned out due to age or heavy use
The fan blade is jammed by debris such as dust buildup, a foreign object, or a deformed blade
The capacitor that starts and runs the fan motor has failed, preventing the motor from spinning up
Wiring to the fan motor is loose, corroded, or damaged
The control board has failed and is not sending the correct voltage signal to the fan motor

How to Fix It

Turn the system completely off at the thermostat and at the circuit breaker. Wait 5 minutes, then turn it back on. Watch and listen for the indoor fan to start — you should hear airflow from the vents within 30 to 60 seconds of the system starting.

A power cycle clears temporary control board errors. If the fan starts normally and the error does not return, the A6 may have been a one-time glitch rather than a mechanical failure.
Check the indoor unit's air filter and make sure all vents are open. A severely clogged filter can cause the fan motor to overheat and trigger an A6 fault. Replace the filter if it is dirty. Also check that nothing is blocking the indoor unit's air intake or outlet.

A fan motor that is overworked against a clogged filter will trigger overheat protection. Once a fresh filter is installed, the motor may cool down and reset.
Listen carefully when the system tries to start. If you hear a humming sound but no airflow, the fan motor may be trying to spin but is stuck or has a failed capacitor. A clicking or scraping sound suggests the fan blade is hitting something. These sounds help diagnose the specific fault.

A humming motor that does not spin is a classic sign of a failed run capacitor — a common, relatively inexpensive repair. A scraping sound means something is physically obstructing the fan blade.
If you are comfortable with basic maintenance, turn off all power to the unit and carefully open the indoor unit cover. Check if the fan blade spins freely by hand. If it is stiff, jammed, or wobbles, the motor or blade needs replacement. Remove any obvious debris caught in the fan.

Always confirm power is off at the circuit breaker before opening any HVAC panel. If in doubt, do not open the unit — call a technician.
Call a licensed HVAC technician for repair. Describe the error code (A6), whether you heard humming or no sound at all, and how old the system is. A technician will test the capacitor, motor windings, and control board to diagnose the exact fault and provide a repair estimate.

On older systems (10+ years), a failed fan motor is often a sign that other components are near end of life. Ask your technician about the overall condition of the system when they are there.

When to Call a Professional

A6 almost always requires a professional repair. Fan motor replacement, capacitor replacement, and control board diagnosis are technical jobs that require the correct replacement parts and electrical knowledge. Call an HVAC technician to diagnose and repair this fault. Expect $150–$450 for a fan motor or capacitor replacement.

Frequently Asked Questions

Can I replace the fan motor myself?

It is possible for a handy homeowner, but it is not recommended unless you are comfortable with electrical work. Fan motors must be matched to the exact voltage, speed, and shaft type of the original. Using the wrong motor can damage the control board or create a safety hazard. If you are confident and have the correct replacement part, follow a model-specific repair video. Otherwise, let an HVAC technician handle it — they can ensure the correct part is installed safely.

What is a capacitor and how can I tell if it has failed?

A capacitor is a small cylindrical component that stores electrical charge and gives the fan motor a starting boost. Signs of a failed capacitor include: the fan hums but does not spin, the motor spins very slowly, or the system struggles to start. A bulging or leaking top on the capacitor is a visual sign of failure. Capacitors can store dangerous electrical charges even when power is off — do not touch them without discharging them first. Replacement is a quick job for an HVAC technician and usually costs $75 to $200 including the part.

My unit is 12 years old. Should I repair or replace it?

That depends on the repair cost versus the system's remaining value. A rule of thumb: if the repair cost is more than half the cost of a new unit, replacement makes more sense — especially on a system over 10 years old. A fan motor or capacitor replacement on an older unit is usually cost-effective. A control board replacement on an older system may not be. Ask your technician for an honest assessment of the system's overall condition before committing to an expensive repair.