No or Poor Airflow Troubleshooting Checklist

No indoor fan:

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. 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 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 uses belt driven motors. Mostly furnaces only, not heat pumps. 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 can always go bad. Sometimes the bearings seize. Or the motor just burns up or weakens.

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

- 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

Not enough airflow:

If there doesn't seem to be enough airflow or it is less than it used to be, there are some things to check before calling for service.

Keep in mind that many of today's high efficiency and electrostatic air filters do restrict more air. They must really be kept clean or they can cause airflow problems.

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

- Faulty indoor blower motor

- Loose, worn fan belt

- Incorrect pulley sizes

- Indoor coil frozen due to malfunction, restricting airflow

- Fan speed set too low, possibly boosting to higher speed

- Blower wheel and/or coil could be dirty

- Ductwork not properly sized or installed

- Debris, obstruction, or closed damper in ductwork

- Dirty filter - the cleaner the filter the better the air-flow

- Make sure vents are open, including return vents

- Make sure dampers are opened - handle should be in-line with duct. Turning handle 90 degrees closes damper

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

We hope this helps. Remember, these are just rough guidelines and not all possible situations are covered.