The answer to 'why is my ductless system not heating' is that there could be several common causes, such as a problem with the compressor, refrigerant leaks, or issues with the thermostat. Symptoms may include the system not turning on, poor airflow, or the unit not producing warm air. Solutions can range from simple DIY troubleshooting to more complex repairs that require a professional HVAC technician.
If the system is not turning on at all, check the circuit breaker or fuse first. Make sure the thermostat is set to 'heat' mode and the temperature is set higher than the room temperature. If those basic checks don't resolve the issue, it's likely a more complex problem that requires professional diagnosis and repair.