Chevrolet LIGHT DUTY TRUCK (SERIES 10-35) Service Manual page 34

Fig. 1A-8-Heater Distributor - G Models
G M odels
Replacement (Fig. 1A-8, 1A-9, 1A-10)
1. Disconnect the battery ground cable.
2. Remove coolant recovery tank and lay aside.
3. Place a clean pan under the vehicle and then
disconnect the heater core inlet and outlet hoses at the core
connections (see "Heater Hoses-Replacement" later in this
section). Quickly plug the heater hoses and support them
in a raised position. Allow the coolant in the heater core to
drain into the pan on the floor.
3. Remove heater distributor duct to distributor case
attaching screws and distributor duct to engine cover screw
and remove duct.
4. Remove engine housing cover.
5. Remove instrument panel attaching screws: above,
at windshield, all lower screws and right lower I.P. support
bracket at door pillar and engine housing.
6. Lower steering column, and raise and support right
side of I.P.
7. Remove defroster duct to distributor case attaching
screw, and 2 screws attaching distributor to heater case.
8. Disconnect temperature door cable and fold cable
back for access (See Fig. 1A-10).
9. Remove three (3) nuts at engine compartment side
of distributor case and one (1) screw on passenger side.
10. Remove the heater case and core as an assembly.
Tilt the case assembly rearward at the top while lifting up
until the core tubes clear the dash openings.
11. Remove the core retaining strap screws and remove
the core.
12. To install a new core, reverse Steps 1-10 above.
Be sure core to case and case to dash panel
NOTICE:
sealer is intact before assembling unit.
HEATER HOSES
Heater hoses are routed from the thermostat housing
or inlet manifold and water pump (radiator on some
automatic transmission vehicles) to the core inlet and outlet
pipes as shown in Figure 1A-9. Hoses are attached at each
end with screw type clamps.
Replacement
The heater core can be easily damaged in the area of
the core tube attachment seams whenever undue force is
exerted on them. Whenever the heater core hoses do not
readily come off the tubes, the hoses should be cut just
forward of the core tubes. The portion of the hose remaining
on the core tube should then be split longitudinally. Once
the hoses have been split, they can be removed from the
tubes without damage to the core.
DISTRIBUTOR DUCTS - G Models
Replacement (Fig. 1A-10)
1. Disconnect the battery ground cable.
2. Raise I. P. at right side as outlined under heater
distributor removal.
3. Unsnap the engine cover front latches. Remove the
two cover to floorpan screws and remove the cover.
4. Remove the heater distributor duct to case attaching
screws as illustrated in Figure 1A-10.
5. Remove one (1) screw at left center of distributor
duct.
6. Pull the center distributor duct to the right and
remove it from the vehicle.
7. To install, reverse Steps 1-5 above.
Check cable and door operation; cables
NOTICE:
should be free from kinks or binding and doors should
close properly. If cable adjustment is necessary, see
"Bowden Cable-Adjustment."
DEFROSTER DUCT
Defroster assemblies attachment is illustrated in Figure
1 A-11 .
CONTROL ASSEMBLY
C-K M odels
Replacement (Fig. 1A-12)
1 . Disconnect the battery ground cable.
2. Remove the instrument panel bezel.
3. Disconnect the bowden cables and the blower switch
wiring harness.
CAUTION: Be careful not to kink the
bowden cables.
4. Remove the control through the opening above the
control.
5. If a new unit is being installed, transfer the blower
switch to the new unit.
6. To reinstall, reverse Steps 1-4 above.
HEATER 1 A-9
LIGH T T R U C K SER V IC E MANUAL