The answer to 'air handler not working' is that there are several common causes, including a tripped circuit breaker, dirty air filters, a malfunctioning thermostat, or a problem with the air handler motor or fan. Symptoms may include the air handler not turning on at all, blowing warm air instead of cool air, or making unusual noises.
If the air handler is not working, first check the circuit breaker and replace any dirty air filters. You can also try adjusting the thermostat to see if that resolves the issue. However, if the problem persists or you suspect a more serious issue with the air handler itself, it's best to call a professional HVAC technician to diagnose and repair the problem. Attempting to service the air handler yourself without proper training and equipment can be dangerous and may cause further damage.