The answer to 'why is my HVAC system leaking water' is that there are several common causes, including a clogged condensate drain line, a problem with the condensate pump, a cracked drain pan, or an issue with the evaporator coil. Symptoms may include water pooling around the indoor unit, moisture buildup, or water dripping from the system.
The best solution depends on the specific cause. For a clogged drain, you may be able to clear it yourself using a wet/dry shop vacuum or by flushing the line. However, issues with the condensate pump or evaporator coil often require professional HVAC service. It's generally best to call an HVAC technician to diagnose and repair the problem, especially if the leak is significant or you're unsure of the cause.