If your furnace starts blowing warm but then quickly turns cold the flame sensor may need attention.
Goodman electric furnace blowing cold air.
This will prevent the exhaust from escaping and cause your issue.
Make sure your flue is open and not blocked or restricted by dead animals.
This video shows step by.
Also make sure all of the supply vents are open and the return air grilles are all clear and unobstructed.
Have an expert inspect your ducts along with the furnace.
Your furnace blowing cold air could be caused by hot air escaping through holes in the duct work that carries the heat throughout your building.
He called me over to help repair his system.
My brother s furnace started blowing cold air one on of the coldest days of the winter.
If your furnace fan is set to on the fan runs continuously whether or not your furnace is producing heat.
So once a heating cycle ends and the furnace burners cut off the fan continues to blow.