The answer to 'water heater blowing cold air' is that there are several common causes, including a faulty thermostat, a broken heating element, or sediment buildup in the tank. This can lead to symptoms like the water heater running but only producing cold air instead of hot water.
To troubleshoot, you'll want to first check the thermostat settings and ensure it's set to the proper temperature. If that's not the issue, you may need to replace the heating element or flush out the tank to remove any sediment buildup. While some basic maintenance tasks can be done DIY, it's generally best to call in a professional HVAC technician to diagnose and repair a water heater blowing cold air, as they have the expertise and tools to properly identify and fix the problem.