Recently encountered a problem with my HVAC system. Fan motor is only a few months old currently.
When a/c is button is "on" The fan blows nice and consistent throughout the 5 speeds like it should. But when I turn the AC off and move the heat to high. The air the fan moves drastically decreases. On speed 1-3 I get almost nothing out of any of the vents. 4 and 5 is still moving way less air than it should be. Also on speed 5 with heat on...the heat only comes out of the middle 3 vents, and barely anything comes out of the 2 far left/right vents. Although when selected to blow on the floor, or defrost, every thing works perfect and blows hard. Although with the AC on everything works exactly as it should. Keep in mind heat itself is not the problem as the air is nice and warm like it should be.
So in short, with heat on fan output is greatly decreased. AC blows exactly as it should.
I am thinking something along the lines of the blend doors, or blend door actuators? Just looking for more opinions