TM 10-3930-659-20 16-15.    HEATER VENTILATORS AND DUCT HOSES REPLACEMENT (Con't). 3. Remove four screws (7), plastic washers (6), heater ventilator (8), and louver housing (1) from cab (5). 4. If damaged, remove two heater ventilators (9) and four spacers (10) from heater ventilator (8). 5. Repeat steps 1 through 4 for other side. TA707011 16-51