Chevrolet 1977 light duty truck Service Manual page 38

N O TE : Be sure core to case and case to dash pane!
sealer is intact before assembling unit.
G Models
Replacem ent (Fig. 1A-9)
1. Disconnect the battery ground cable.
2. Place a clean p a n under the vehicle and then
disconnect the heater core inlet and outlet hoses at the
core connections (see " H e a te r Hoses-Replacem ent" 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 p a n on the floor.
3. Disconnect the right h an d air distributor hose
fro m the heater case and rotate it up out o f the way.
4. Pry off the tem perature door cable eyelet clip
and then remove the bowden cable attaching screw.
5. Remove the distributor duct to heater case
screws and pull the duct rearw ard out o f the heater case
retainer.
6. Remove the four heater case to dash screws and
then remove the heater case an d core as an assembly.
Tilt the case assembly rearw ard at the top while lifting
up until the core tubes clear the dash openings.
7. Remove the core retaining strap screws and
remove the core.
8. To install a new core, reverse Steps 1-7 above.
N O T E : Be sure core to case and case to dash panel
sealer is intact before assembling unit.
HEATER HOSES
H eater hoses are routed
housing or inlet m anifold and w ater p u m p (radiator on
some automatic transmission vehicles) to the core inlet
and outlet pipes as shown in Figure 1 A - 10. Hoses are
attached at each end with screw type clamps.
Replacem ent
The heater core can be easily dam aged in the area
from the tnermostat
o f the core tube attachm ent seams whenever undue force
is exerted on them. W henever the heater core hoses do
not readily come off the tubes, the hoses should be cut
just forward o f the core tubes. The portion o f the hose
rem aining on the core
longitudinally. Once the hoses have been split, they can
be removed from the tubes without d am age to the core.
CENTER D IS T R IB U T O R D U C T - G Models
Replacement (Fig. 1A -11)
1. Disconnect the battery ground cable.
2. U nsnap the engine cover front latches. Remove
the two cover to floorpan screws and remove the cover.
3. Remove the heater core case and core as an
assem bly (see " H e a te r
Replacement").
4. Disconnect the right h a n d heater outlet hose
and the two defroster hoses from the distributor duct.
5. Disconnect the air and defroster door cables by
prying off the eyelet clips and removing the cable
attaching screws.
6. Pull the center distributor duct to the right and
remove it from the vehicle.
7. To install, reverse Steps 1-6 above.
NOTE: Check cable and door opeation; cables
should be free from kinks or binding and doors
should close properly.
necessary, see "Bowden Cable-Adjustment."
LEFT D IS T R IB U T O R DUC T - G Models
Replacement (Fig. 1A -11)
1. Disconnct the battery ground cable.
2. U n snap the engine cover front latches. Remove
the two cover to floorpan screws and remove the cover.
3. Remove the duct bracket screw and remove the
duct.
4. To install, reverse Steps 1-3.
N OTE: All three bowden cables are routed under
the duct. It m ay be necessary to hold the cables
down as the duct is being installed. Be sure the left
duct is fully installed over the center duct.
DEFROSTER DUCT
The defroster hose
illustrated in Figure 1 A -12.
CO N TR O L ASSEMBLY
C-K M odels
Replacement (Fig. 1A -13)
1. Disconnect the battery ground cable.
2. Remove the instrum ent panel bezel.
3. Disconnect the bowden cables and the blower
switch wiring harness.
tube should then be split
D is trib u to r and Core-
If cable adjustm ent
and outlet assemblies are
is