FAN RUNS CONTINUOUS – The thermostat maintains the correct temperature, but the indoor fan never quits blowing.

POSSIBLE PROBLEM & DESCRIPTION

Thermostat “Fan” Switch

The most common cause of this problem is the “Fan” switch on the thermostat. It normally has two options – “Auto” and “On”. In the “Auto” position, the fan should cycle on only when there is a call for cooling. In the “On” position, the fan will run continuously.

Some new thermostats have an additional fan setting of “Circ”, which is short for “Circulate”. In this mode the fan will cycle on and off with the cooling, but it will also kick-on automatically if there is an extended period without a demand for cooling – to provide additional air circulation.

Stuck Blower Relay – Qualified Technician Recommended

All furnaces have either a fan relay or a control board to cycle the fan on and off as needed. Sometimes the relay or control can stick which will cause the fan to run continuous.

Cooling Problems – Qualified Technician Recommended

A problem with the air conditioning unit will often make it appear that the indoor fan motor is stuck on. What may actually be happening is that the thermostat is calling for cooling but the indoor temperature never drops enough to tell the thermostat to shut off. In this case the fan will run as long as the thermostat is asking for cooling.