The answer to 'HVAC repair not heating' is that there could be several common causes, including a malfunctioning thermostat, a problem with the furnace or heating system, issues with the ductwork, or a lack of maintenance. Symptoms may include the home not getting warm enough, the furnace not turning on, or uneven heating throughout the house.
Some potential solutions include checking the thermostat settings, replacing air filters, inspecting the furnace for any issues, and ensuring the ductwork is properly sealed and insulated. However, for more complex problems or if you are not comfortable troubleshooting the issue yourself, it's best to call a professional HVAC technician to diagnose and repair the issue.