The answer to 'my ductless system won't turn on' is that there could be several common causes, such as a tripped circuit breaker, a faulty thermostat, or issues with the indoor or outdoor units. First, check the circuit breaker and reset it if tripped. If that doesn't work, inspect the thermostat to ensure it's set properly and has power. If the thermostat seems fine, the problem may be with the indoor or outdoor unit, which will likely require a professional HVAC technician to diagnose and repair.
Ductless systems, also known as mini-splits, are complex systems that require specialized knowledge and tools to service properly. While some basic troubleshooting can be done by a homeowner, it's generally best to call in a professional HVAC technician to diagnose and fix any issues with a ductless system. Attempting to repair it yourself could lead to further damage or safety concerns.