The answer to 'why is my furnace blowing hot air' is that there are several common causes, including a clogged air filter, a problem with the thermostat, or an issue with the furnace itself. Symptoms may include the furnace running constantly, uneven heating, or the air coming out of the vents being too hot.
Some potential solutions include replacing the air filter, checking the thermostat settings, and ensuring the furnace is receiving power and functioning properly. If the issue persists or you're unsure of the cause, it's best to call a professional HVAC technician to diagnose and repair the problem.