The answer to 'why is my humidifier not turning on' is that there could be several common causes, such as a tripped circuit breaker, a faulty humidistat, a clogged filter, or an issue with the water supply. Symptoms may include no power to the unit, the humidistat not registering humidity levels, or the humidifier not producing any mist.
To troubleshoot, first check the circuit breaker and reset it if tripped. Next, inspect the humidistat and ensure it is set to the correct humidity level and functioning properly. Clean or replace the filter if it is clogged. Finally, check the water supply line for any blockages or leaks. If you are unable to identify and resolve the issue, it's best to call a professional HVAC technician to diagnose and repair the humidifier.