Find your heater and trace the duct paths. Sometimes where the ducts connect to the heater box, the connections dislodge, or the same could happen near the registers. Inspect the ducting for tears and kinks. In my case, I had to switch the ducts around to get flow to the right place. Way too much was going to the basement and we got too little heat where we needed it.
Dan and Rita
Prefer not to be hooked up in a RV park
2015 Outback 286 FRL Diamond
4x4 Automatic TurboDiesel Shortbed