TM 10-3930-659-20 16-15.    HEATER VENTILATORS AND DUCT HOSES REPLACEMENT (Con't). NOTE Perform steps 5 through 9 to install heater ventilators and duct hoses on cab. 5. If removed, install four spacers (10) and two heater ventilators (9) on heater ventilator (8). 6. Install louver housing (1) and heater ventilator (8) to cab (5) with four plastic washers (6) and screws (7). 7. Position two hose clamps (2) on duct hose (3). 8. Install duct hose (3) on louver housing (1) and duct (4), and tighten two hose clamps (2). 9. Repeat steps 5 through 8 for other side. TA707014 16-54