4-12. CAB - Continued
(1) Crimp heater hoses using suitable pliers to prevent loss of engine coolant. Remove inlet and outlet
winterization hoses and clamps (A) (below cab floor).
(2) Loosen hose clamps (5 and 6) and disconnect flex hoses (7 and 8).
(3) Loosen hose clamps (24 and 25) and pull heater hoses from barbed nipples.
(4) Remove screws (11) and nuts (12) and pull heater unit out of cab.
(5) Tag and cut the wires (13 and 14) as well as the colored blower motor wires. Cut the wires as close as
possible to the butt splices (21).
(6) Remove screws (15) and nuts (16) and remove blower unit.
(1) Inspect heater box components for superficial damage and defects. A trace of crystal deposit left by
evaporated coolant often indicates a potential leak or a weak joint. If any traces or deposits are noticed,
test the components as detailed under Heater Core and Plumbing Repair following.
(2) Check that the movement of diverter arm (23) is smooth and unobstructed and that the heater core is
solidly attached to the heater box. Tighten the attaching screws if necessary.
(3) Inspect flexible hoses (8, 7, and 18) as well as the air diffusers (19 and 20). Replace damaged hoses if
the air diffusers (19 or 20) are damaged, notify Direct Support Level for repair.
Use flexible hose (64 - 2920X) and cut to appropriate length when replacing Items (7, 8, and 18).
(4) Inspect the blower unit. Check that blower wheels and housings do not rub against one another.
Rubbing caused by minor damage to the housing may be eliminated by straightening dents or bends in
(5) Inspect bulkhead fittings (10) and barbed hose fittings (9). Fittings with stripped thread or surface
damage that could cause leaks must be replaced.
(1) Install blower unit (17) to cab floor using six screws (15) and nuts (16). Tighten nuts firmly.
(2) Install heater box (4) complete with heater core. Attach box using six screws (11) and nuts (12).
(3) Attach heater hoses to 'barbed nipples on floor of cab. Tighten clamps (24 and 25).