Understanding HVAC Issues

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How to Troubleshoot an AC Blower that Isn't Working

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If you have a central air conditioning system that cools down your home, then one of the major parts of the system will sit inside your house. This is the air handler or evaporator that moves cool air into your house. Air is cooled by the evaporator coils and then blown up through the vents. A blower helps the air move, and this part may need some maintenance if you notice that only a small amount of air is coming through the vents. Keep reading to understand how to maintain the blower.

Locate the Part & Complete an Inspection

Before you complete any maintenance on the blower, you will need to locate and inspect the part first. The blower, fan, and motor take up a large space in the air handler system, and the parts can typically be accessed through a panel along the side of the condenser unit. Look for the access panel close to the bottom of the unit and remove any screws or clips that keep the panel in place. Once the panel is removed, you will see a circular part with a vent on one end. This is the blower and the middle will be open. This will allow you to see the blades of the fan inside the blower unit. The fan will look much like a hamster wheel, and it is sometimes called a squirrel cage fan for this reason. Inspect the fan blades for debris. Sometimes, the fan blades will build with dust and this will compromise the function of the blower. Use the hose and brush attachments on your vacuum cleaner to remove the debris. Also, clean around the side of the blower.

When you are done cleaning, look for any belts that may be attached to the blower unit. Many AC blowers are direct drive units with an attached motor. The motor connects to the blower compartment with the help of a shaft or fan axle. However, your unit may have a belt driven motor instead. This type of device will have a fan that connects to a motor that sits outside the blower compartment, and the fan will be connected with several different belts. If you see any belts, then check them for any signs of wear and tear. If you see damage, then replace the belts as soon as possible, or ask your HVAC professional to complete the job for you. 

Watch & Listen to the Blower

Once an initial investigation is completed, you should try to activate the fan so you can see if it is working or not. Turn your thermostat to fan or cool to activate it. If the fan blades along the squirrel cage do not move, then you may need an entirely new fan motor or blower assembly, depending on the type of drive motor that is installed. This is a job that should be completed by an HVAC expert.

If you see the fan moving, but it moves slow, then you may need to reset the electric motor overload switch. This is also a possibility if the motor seems noisy or if it seems as though it has difficulty starting. Another sign that the switch needs resetting is if you notice that the fan moves slow and then fast when the blower has been running for several minutes. The electric motor overload switch is a safety device that trips if the motor becomes too hot. The switch essentially turns off the motor so it does not overheat completely. While the switch might reset itself, you may need to reset it manually.

To reset the overload switch, look for a small button on the side of the fan motor. It is likely to be a small red button. Press the button and it should pop in. Start the fan up again to see if it works. If it does not, then the capacitor may not be working correctly. The fan capacitor is a small electronic starter that provides the fan with a jolt of electricity so the fan and blower can start working. Capacitors are wired directly to the fan motor, so they are fairly easy to locate and replace. However, if you are unfamiliar with electrical work, then it may be safer to ask a professional for assistance.