The answer to 'why is my air handler short cycling' is that your air handler is rapidly turning on and off in short bursts, rather than running for longer, more efficient cycles. This can be caused by a few common issues, such as a problem with the thermostat, a blocked air filter, or issues with the air handler itself.
Short cycling can waste energy, put strain on your HVAC system, and lead to uneven cooling or heating in your home. It's important to identify and address the root cause to restore proper, efficient operation of your air handler. In some cases, this may be a simple DIY fix, but more complex issues may require the expertise of a professional HVAC technician.