Fan Coil Unit Maintenance

A fan coil unit (FCU) is a device which heats or cools a room using a fan and coil. In this article we will discuss what they are, how they work, and how to perform fan coil unit maintenance.

A close up look at a fan coil unit.

What Are Fan Coil Units?

Several types of FCUs exist. Some FCUs use ducting while others do not. Just as some FCUs are part of an air handler system while others are not. They often come in vertical and horizontal configurations that can be floor mounted, ceiling mounted or recessed within a wall. Many units are designed to work independently, but some are tied in as part of an HVAC system. FCUs can also be connected to a building automation system including a thermostat and be managed via a central panel or on a computer.


  • First, a fan draws air into the unit.
  • Next, the fan blows the air over a cooling or heating coil.
  • The coils are either cooled with chilled water or heated with hot water (or electricity in some cases).
  • Then, the air comes out of the FCU either cooler or warmer than before.
  • Note: this process is slightly different depending on whether the FCU has two or four pipes.

Fan coil diagram with 2 pipe vs 4 pipe configuration.

These units are great for when you have multiple small spaces that require individual control. They also tend to come in at a lower price point than traditional systems and can be installed less invasive. On the negative side, these units are not as powerful as traditional systems and don’t lend themselves to heating and cooling large open spaces. They also require chilled water valves and hot water valves which can be a maintenance problem.


  • Before performing any maintenance on your FCU, you should follow proper lockout procedures. This way the unit won’t be operational while being serviced.
  • Always inspect the inside and outside of the unit and remove any debris and dust. Be sure to remove dust from the motor and blades. Dust build up on the blades could cause them to become unbalanced.
  • Change the filter every time you perform preventative maintenance. 
  • Oil tubes should be lubricated with a 20-weight non-detergent oil to ensure all moving parts are moving freely. Do not lubricate ball bearings.
  • No oil tubes? If your FCU does not have oil tubes see your operating manual for lubrication instructions.
  • Replace dry, cracked, or worn down belts.
  • If coils require cleaning, remove motor/blower assemblies and brush between fins. Follow this up by vacuuming the fins. Alternatively you can use a compressed air system to blow air through the coil fins from the exiting air face.
  • If the motor is making odd sounds, vibrating, or not working at all call a technician for additional repairs.

Recommended Fan Coil Unit Maintenance


  • Inspect the exterior of the FCU. Remove any debris.

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  • Inspect the interior of the FCU.
  • Remove dust on the motor and fan.
  • Inspect the belts. Replace if needed.
  • Inspect the filter. Replace if needed.


  • Lubricate the motor with a 20-weight, non-detergent oil. Some FCUs require more frequent lubrication. For example, those operating in especially dusty weather should be lubricated more often. Keep in mind over-oiling could reduce motor life. – Do not oil the bearings.
  • Clean the drain area to ensure air flow.
  • Brush and vacuum the coil.


  • Schedule annual maintenance with a technician.
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