The answer to 'why is my air handler not working' is that there could be several common causes, such as a power issue, a clogged air filter, or a problem with the thermostat or control board. The air handler is the indoor unit that circulates the air through your home's ductwork, and if it's not working, it can lead to problems with your home's heating and cooling.
Some common symptoms of an air handler issue include the unit not turning on at all, the air not circulating properly, or strange noises coming from the unit. Potential solutions can include checking the power supply, replacing the air filter, or troubleshooting the thermostat or control board. However, if you're not comfortable diagnosing and repairing the issue yourself, it's best to call in a professional HVAC technician who can properly identify and fix the problem.