Table 2-2. Operator/Crew Preventive Maintenance Checks and Services (Contd). ITEM NO. INTERVAL ITEM TO CHECK/ SERVICE PROCEDURE NOT FULLY MISSION CAPABLE IF: TM 9-2320-386-10 2-38 Change 1 With engine shut off, ensure air dryer Air dryer heater heater (1) is functioning properly. fails to operate at Touch heater (1). If functioning temperatures of 53°F properly, heater (1) should feel warm. (12°C) and below. 37 Air Open drainvalves (3) on air reservoirs reservoirs (2) and exhaust air completely. NOTE • Air dryer heater must be checked immediately after shutting down engine. • Air dryer heater only operates at temperatures of 53°F (12°C) and below. 3 2 VEHICLE EXTERIOR ENGINE NOT RUNNING 36 After Air dryer Operation heater (Contd) WARNING • Use caution when checking air dryer heater. A malfunc- tioning heater may be too hot to touch and cause injury to personnel. • Air dryer heater operates at temperatures of 53°F (12°C) and below. Air dryer heater failure may result in equip- ment damage and injury or death to personnel. 1