Your air conditioner and furnace both have a motorized fan that plays a key roll in the heating or cooling process. If the motor experiences operational issues, or stops working completely, your HVAC system efficiency and indoor comfort will both suffer.
There are a few signs that can point towards a fan motor problem being the culprit behind your heating and cooling woes. If you can't narrow down the problem, call in an air conditioning services company to examine the system.
Overheating Condenser Coils
The motorized fan in the air conditioner's condensing unit aims ambient air at the condenser coils to prevent overheating. The coils take in gas refrigerant from the compressor then change that gas to a liquid, which causes the coils to become warm. If the coils became overly warm, the phase change would suffer and the system's safety mechanism would trigger a total shutdown to protect the parts from damage.
A dying fan motor can slow the speed of the fan blades, which reduces the amount of ambient air hitting those coils and can lead to a shutdown. If your air conditioner turns off suddenly for no clear reason, the problem might be the fan motor.
The condensing unit fan and the fan inside the furnace can both become louder when the motor starts to go. The noise comes from the fact that the motor isn't able to spin the fan blades as quickly or smoothly on the motor shaft. Motor-related noises might sound like mechanical whining or squealing.
Note that a fan making a thumping noise might have a problem with the fan blades rather than the motor. Fan blades can come loose from the shaft or bend or break in a way that causes the blades to hit other parts of the unit while spinning.
No Hot or Cold Air Leaving Your Vents
The blower motor inside the furnace is what pushes out the hot air produced in that system. But the motorized fan also pushes out the cold air produced in the air handler, or indoor portion of the air conditioner that's usually housed inside the furnace to save space. So if you don't have hot or cold air coming out of your vents but the units seem to work fine otherwise, the problem is likely with the blower motor.
If a small amount of air comes out, the problem could either be the motor dying or the fan blades. The fan blades are a cheaper and easier fix.
If you're experiencing these or similar problems with your HVAC system, contact a service like Allied Mechanical & Electrical, Inc. for assistance.