In newer buildings with a central heating and cooling system, fan coils may be located behind a panel in the wall of one or two rooms in each suite along with the thermostat. At the bottom, there is an air filter with the in-vent and above is the motor for the fan and coil with a pan under to prevent condensation from dripping. The exhaust vent is above.

When the thermostat is on A/C or heating, the fan simply re-circulates air that is already in the room after the system has either cooled it or warmed it. The air does not come from outside. This is why, if this system is to work properly, no furniture should be placed in front of the grill where the air filter is. This is where the air goes in to be cooled down or heated up.

It’s a good idea to air a room regularly by opening a window but this should be done only when A/C or heating are not on. Otherwise, energy will be wasted and the motor will work harder and burn out prematurely.

This maintenance is necessary for proper functioning and to prevent leakages as well as mold formation. When furniture is placed in front of the air intake (where the filter is), the system can’t get air in and the motor may burn out prematurely.