TM 9-2320-209-20-3-4 a. Removal. FRAME 1 NOTE Note position of heater control switch before taking it out so that it can be put back the same way. 1. Using 1-inch wrench, unscrew and take off locking nut (1). Take heater control switch (2) from switch mounting bracket (3) from back of instrument panel (4). GO TO FRAME 2 23-46