I have a bunglow home, my problem is during the summer the upstairs does not cool down and during the winter it does not heat up I've noticed that there is no cold air
Return just one air duct. I checked to make sure that the vent was not shut off coming from the furnace and the vent does blow good air but not to heat up or cool down.
What do I need to fix the problem?

>Moved from Forum Help<

Add ducts to the upstairs. Could be a lot of work

Use a small space heater in the winter and use a window A/C unit in the summer. Less work.

There are also other HVAC units on the market called mini splits that would also work up stairs and will supply both heat and cool. Better hire a pro for this one.