How to Check a Fan Coil with a Multimeter

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The fan coil is a device that takes in outside air and pushes it through a heating and cooling coil to either warm it up or cool it down. But what happens when the fan coil stops working? How can I troubleshoot the fan coil?

What is a fan coil?

Fan coils, or air handling units (AHU), are a common fixture in commercial and industrial buildings, used to deliver heat and/or to cool the entire building. They are usually installed in central locations and deliver their air through ductwork. 

The temperature of the air delivered is controlled by the fan, which is driven by the variable frequency drive (VFD), or variable speed drive (VSD) that is installed on the fan. The output of the fan is monitored by the VFD, which changes the speed as necessary to keep the building within the desired temperature range.

Have you ever wanted to know how to check if a fan coil is faulty or fix it yourself? 

For those that don’t know, a fan coil is a device that moves air using a motor and a heat exchanger. They are used in environments where heating or cooling is required, such as a computer room, and are often found in conjunction with air conditioning units on the outside. 

A fan coil is a very complicated system and is one of the more difficult systems in an HVAC unit to troubleshoot. However, with a multimeter and some knowledge of how fan coils work, you can figure out what is wrong with your unit.

A fan coil (also known as a chiller unit, air handler, or economizer) is a mechanical device that moves air throughout a building. This air is usually used to cool the building or heat it. 

It uses a fan to distribute air through ducts. A fan coil unit is normally used for large buildings (such as large office buildings or factories) but can also be used in a home. It can have several different parts, and you can check those to see if they are faulty.

The fan coil system is a popular product in the residential and commercial industries. As a result, there is a wealth of information available on how to check a fan coil with a multimeter. 

The most popular method is to kick off a fan coil’s power and then place your multimeter’s probes across the fan coil’s terminals. This method works well even if the fan coil is powered on.

Testing the coil using a multimeter

The fan coil is one of the most important components of a HVAC system. When your heating or cooling system malfunctions, the problem often lies with a faulty fan coil. 

If you’re not trained in HVAC repair, the only way to find out what’s wrong with a fan coil is by testing it with a multimeter. The multimeter can tell you if the fan and heating and cooling system are functioning correctly.

Here are the steps for preparing the fan coil for testing:

  1. The first step in checking a fan coil is to disconnect it from the control circuit and confirm what type of control you are dealing with: a speed control, a two- or three-wire control, or a variable frequency drive control. 
  2. Then, you can move on to the next step, which is to disconnect the fan coil’s power supply and confirm that there is no voltage present at the fan coil.
  3. The next step is to remove the fan coil access panel, which is located on the outside of the heat loop.
  4. Then, you should disconnect the wires and remove the cover.
  5. The last step is to get your multimeter out. 

Here are steps for you to follow on how to test a fan coil with a multimeter:

  1. Read the instruction manual of the multimeter you will use to troubleshoot the fan coil.
  2. Set the multimeter to the ohms setting.
  3. Connect the multimeter to the fan coil.
  4. Set the multimeter to the 200-500 ohm range setting.
  5. Read the multimeter and note down

You may never find yourself in the position of troubleshooting a fan coil, but it’s always good to be prepared. And what better way to prepare than by taking the time to learn how to check a fan coil? 

A fan coil is an apparatus used to heat and cool spaces in a building. Most of these systems are designed for commercial buildings, but they are also used for residential purposes. 

The first step when figuring out how to check a fan coil is to locate the fan coil’s control board. This can be found inside the unit and should be clearly labeled.

Important things to remember

If you are not familiar with the fan coil, it’s a type of HVAC system that provides heating, cooling, and ventilation through a single system. 

This system uses an internal fan to circulate air throughout the building. An HVAC technician can use a multimeter to test this system for proper operation.

When checking a fan coil with a multimeter, it is important to always take into consideration the following: 

  • The power supply must be in good working order. 
  • The fan must be in good working condition. 
  • The temperature sensor must be in good working condition. 
  • The airflow must be sufficient. 
  • The temperature sensor must be calibrated for the outside air temperature. 
  • The temperature sensor must be calibrated for the desired inside temperature.

Whenever you need to troubleshoot a fan coil and are in doubt: Check the power fuses or circuit breakers first. What I mean by this is to check the 115V line and the 230V line. If they are both good, then the problem is most likely in the fan coil unit.

In the world of industrial, commercial, and residential air conditioning and heating, fan coils are a common sight. They are used to extract heat from a building and transfer it to the open air or into the ground, where it can be used as part of a geothermal heating and cooling system. Because fan coils are at the heart of these systems, it’s important to know how to check them with a multimeter.

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