If your indoor fan isn't working it could be several things. We will go over a few things to check before calling for service.

First make sure there is power to the indoor unit and that a switch or breaker isn't off. Some indoor units (Heat Pumps) have breakers right on the Air Handler itself. But also check the main breaker panel. Some units have a shutoff switch on the side of the unit or an Emergency Switch located on a wall.

Then make sure your air filter isn't blocked. Sometimes that is the only problem. Some customers don't even know they have an air filter and it has never been checked. Try setting the thermostat fan switch to the "on" position. Feel for air coming out of the vents.

If it is in the air conditioning mode, check for ice around the evaporator coil and on the refrigerant lines at the indoor unit. If the coil froze, the fan could be working but the air wont go through the ice until it melts. If the fan isn't working, that can cause the coil to freeze. If the coil is frozen, shut off the air conditioning immediately. Then check-out our page on heat pump iced-up in summer. (Even if it's not a heat pump.)

Some equipment still use belt driven motors. Mostly "low-boy" oil furnaces, especially older models. Sometimes the belts wear out, crack, and eventually break. If you take a look at the blower section of your heating system it is quite easy to see if you have a belt driven blower motor. You will see a motor sitting on top or next to a larger blower wheel connected by a fan belt.

Most fans are energized by a fan relay. This is probably the most common cause. The contacts inside the relay go bad. They usually stick open, never sending the signal to the motor. This is much easier and cheaper to repair than a motor going bad.

Of course, the motor itself can always go bad. Sometimes the bearings seize. Or the motor just burns up or weakens.

Below is a list of possible causes. Items in red usually require a service call. Items in blue however can be addressed, some even fixed by the homeowner.

Red = Professional fix | Blue = Homeowner fix

Faulty relay or fan control
Faulty motor
Faulty fan belt
Bad wiring
Faulty thermostat
Frozen coil due to an air conditioning problem
Bad or weak motor capacitor

Breaker or switch off
Filter completely blocked

The bottom causes in blue are commonly found problems and can be addressed by the homeowner. Try to check for these conditions first before calling for service.