When a stopped fan is normal
The outdoor fan and compressor don't always start together, and inverter units slow or stop the fan when it isn't needed, especially in mild weather. In heating mode, frost builds on the outdoor coil on cold, damp mornings. The unit stops its fan and reverses for a few minutes to melt it, often with a hiss, a cloud of steam and water dripping underneath. Heating then resumes on its own.
If the fan starts again within several minutes and the house is heating or cooling properly, there's nothing to fix.
When it's a fault
If the outdoor unit is humming or the compressor is running but the fan never turns, heat can't escape, and the unit soon stops on high pressure, usually with a flashing light or error code. Indoors, the air may turn warm in cooling mode. Common causes are a failed fan motor, a weak capacitor, a faulty sensor or control board, or something jamming the blades, such as a stick, a nest, leaves or built-up ice.
A fan that turns slowly, grinds or squeals has worn bearings, which usually end in a seized motor if they're left.
What to do
Turn the unit off at the remote and leave it off if the fan stays still while the unit runs, or if you smell burning. Running it like that strains the compressor, the part you least want to replace. Don't push sticks or fingers through the grille or try to spin the fan by hand, because the capacitor and wiring can hold a charge. Fan motor and capacitor faults are repaired by a licensed technician.
What you can safely do now
- Wait several minutes, especially on a cold morning, in case it's a defrost cycle.
- Look through the grille from a safe distance for sticks, leaves or a nest.
- Turn the unit off at the remote if the fan stays still while the unit hums or the air turns warm.
- Note any flashing light or error code on the indoor unit.
- Keep plants and stored items clear of the outdoor unit.
Services that can help
Read more in our guides
Related questions
- Why is there ice on my air conditioner pipes?Ice on the pipes or coil in cooling mode means the coil is running colder than it should.
- What is the switch next to my outdoor unit for?It's an isolating switch that cuts all power to the air conditioner, so a technician can work on the system safely without relying on the switchboard.
- My air conditioner won't respond to the remote. What can I check?Start with the remote: fresh batteries, a clear line to the indoor unit, and no lock symbol or odd mode on its display.
- My air conditioner won't restart after a power outage. What now?Give it a few minutes first.
General information for homes in Victoria. Every installation is different, so treat this as a starting point. Where this answer refers to Victorian safety or rental rules, the sources above have the current requirements.