The answer to 'my HVAC system won't turn on' is that there could be several common causes, such as a tripped circuit breaker, a faulty thermostat, or a problem with the HVAC unit itself. The symptoms may include the system not powering on at all, the fan not running, or the system not producing hot or cold air as expected.
For a simple issue like a tripped breaker, you may be able to reset it yourself. However, if the problem persists or you're unsure of the cause, it's best to call a professional HVAC technician to diagnose and repair the issue. They have the expertise and tools to properly identify and fix the problem, ensuring your HVAC system is running safely and efficiently.