I have a Nordyne model # W6H1502B 5 years old. It is not warming my house up. It used to but I don't know what's going on. Seems to me that some vents there's hardly any air blowing or none and the vents that are blowing is not hot air??

Before we get to your furnace what's the temperature outside? What's the temperature inside? What is your thermostat set on? Where is your thermostat located at? Is there a part of your house warmer or colder than the others? Sorry for all the questions, just need the info.