TM10-3930-660-34 CHAPTER 15 BODY AND CHASSIS ACCESSORY ITEMS MAINTENANCE Section I. DESCRIPTION AND DATA 15-1.  MAINTENANCE TASK SUMMARY. This chapter covers maintenance procedures for the cab heater, as well as a functional description of the cab heater. 15-2. DESCRIPTION AND DATA. a. Heater.  The heater is located beneath the operator’s seat in the cab. Engine  coolant is supplied to the heater core through flexible hoses. A pair of  blowers draw air through the heater core where it extracts heat and discharges the heated air along the floor of the cab. b. Heater  Controls.    A  manually  operated  valve  located  in  the  coolant  supply  line    controls  heating  capacity  of  the heater by regulating the flow of coolant to  the heater core. This valve can be fully closed to completely shut off coolant  flow to the heater core. Control of this valve is by means of a push-pull knob  located on the side console. Pulling up on the knob increases the heater  temperature setting. Pushing down on the knob decreases the heater temperature  setting. A three-position switch, also located on the side console, controls heater  blower speed. LOW position of the switch produces the slowest blower speed and  HIGH position produces the highest blower speed. The OFF position removes power  from the heater blower motor and the motor shuts off. Section II.  BODY AND CHASSIS ACCESSORY ITEMS MAINTENANCE PROCEDURES BODY AND CHASSIS ACCESSORY ITEMS MAINTENANCE TASK SUMMARY TASK PAGE PARA . PROCEDURES NO. 15-3 24V Heater Assembly - Repair 15-2 15-1