Heat pump fan not spinning: what to check before you call
A still fan is sometimes normal. When it is not, one part of the diagnosis is firmly a job for a licensed pro.
If your heat pump's outdoor fan is not spinning, first check whether it is supposed to be. In defrost mode, or while the system is idle, the fan can sit still for good reason. If it should be running and is not, the cause is usually electrical.
Do not poke at it. Start with the safe checks below.
Check that the system is calling for heat or cooling
Set the thermostat a few degrees past the room temperature in the mode you want. If the setpoint is already met, the outdoor unit stays quiet. Make sure the mode is right and the thermostat has power.
A paused fan can be normal
During a defrost cycle, the outdoor fan usually stops for a few minutes while the unit melts frost. After a power interruption, the unit also waits several minutes before restarting. Give it at least five minutes before you decide anything is wrong.
Look for the compressor, too
Is the compressor humming while the fan sits still? Or is the whole outdoor unit silent? The first points to a problem in the fan circuit. The second points toward power, the thermostat signal or a safety shutdown. Tell the technician which one you saw.
Check the breaker and the disconnect
Look at the outdoor unit's breaker and the disconnect box near it. Reset a tripped breaker once. If it trips again, leave it off. A repeat trip is a fault, and forcing it can cause damage.
Look from a distance for obstructions
From a few feet away, check for heavy ice, packed snow or debris around the cabinet. Clear loose leaves and snow by hand. Do not chip at ice with tools, because the coil fins are easy to damage.
What not to do
- Do not push the fan blades with a stick or your hand to get it going. Blades can start suddenly and cause serious injury.
- Do not open the outdoor unit or touch the electrical parts inside. A capacitor in there can hold a dangerous charge even when the power is off.
- Do not add or check refrigerant. It requires federal EPA Section 608 certification.
When to call a licensed HVAC technician
Call one if the fan stays still after the delay and the thermostat and breaker check out. Also call if you hear humming from the unit or the breaker keeps tripping. The cause is inside the cabinet, and that is electrical work for a licensed professional.
Frequently asked questions
Why is my heat pump fan not spinning but the unit is humming?
A hum with a still fan points to a problem in the fan circuit. Turn the system off at the thermostat and call a licensed HVAC technician.
Is it normal for the heat pump fan to stop?
Yes, briefly. It stops during defrost cycles, during restart delays and when the thermostat is satisfied.
Can I spin the fan by hand to restart it?
No. The blades can start suddenly and cause serious injury. Leave it to a licensed technician.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- ENERGY STAR. Air-Source Heat Pumps
- ENERGY STAR. Energy Savings at Home: Heating & Cooling