Why is cold air coming out when the heat is on?

This issue could be caused by an improper thermostat setting. Check that the fan blower switch is set to “auto” and not “on.” When the “auto” setting is chosen, the fan will only run during a heating cycle and won’t push air that feels cooler through the vents in between cycles.

Why is my heater not that hot?

As seen above, different reasons can make your heater fail to blow out hot air. These reasons include an incorrect thermostat setting, broken ductwork, dirty air filters, wrong-sized heater units, and dirty flame sensors.

What do I do if my heater is blowing cold air?

How To Troubleshoot Furnace Blowing Cold Air

  1. Step 1: Check Thermostat Setting. First and most importantly, make sure your thermostat is set to Heating Mode. …
  2. Step 2: Evaluate and Adjust Your Vents: …
  3. Step 3: Assess Furnace Filters and Replace Filters If They Are Dirty. …
  4. Step 4: Call An HVAC Pro.