Hi. I don't know much about furnaces but here is the problem as best I can describe. The air was on and worked fine. After awhile, the house got hot and I noticed that the air was barely moving through the vents. I would appreciate any advice I can get!

Your coil on the inside unit is freezing up. This is caused by lack of air flow, dirty air filter,dirty inside or outside coils Fan indoor or out, not running up to full speed of low on refrigerant due to a leak