1. Remove the front seats. 
2. Remove the front side sill cover.
3. Turn over the floor mat and remove the cover of the part engaging the heater unit, then remove the heater duct.
HVAC SYSTEM (HEATER, VENTILATOR AND A/C) > Heater Duct
1. Remove the front seats.
2. Remove the front side sill cover.
3. Turn over the floor mat and remove the cover of the part engaging the heater unit, then remove the heater duct.