Chevrolet 70 1969 Series, Shop Manual

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CAB AND BO DY M O U N T IN G S 1-31
Figure 32— Heater Control Cable Adjustment Sleeve
I N S T A L L A T I O N
1. Make sure the cellular dust pad is located
over heater core water inlet and outlet pipes.
2. Place the heater core and blower assembly
into position then install all attaching bolts.
IM P O R T A N T : Make sure blower motor ground
wire is sandwiched under head of heater support
bracket attaching bolt at dash panel.
3. Connect wiring at blower speed control re­
sistor unit and also at the blower motor. Make
sure connections are secure.
4. Connect the blower air outlet tube.
5. Connect the "A IR " and " T E M P ." controls
to heater assembly. Lower view in figure 31 shows
connections.
6. Referring to identification marks made on
heater hoses prior to disconnecting, connect the
hoses to respective heater core piping.
IM P O R T A N T : Make sure the 5/8 inch I.D. hose
is connected to small core pipe and that the 3/4
inch I.D. hose is attached to the larger pipe. If
hoses are not installed as directed, poor heat Out­
put and/or a ruptured heater core will result. The
core internally is designed to accept the higher
pressure at the inlet (5/8 inch I.D. pipe) side of
core only.
7. Replenish coolant in system then start and
operate engine until normal operating temperature
is obtained.
8. Check for possible leakage and check the
operation of heater and controls.
AIR DISTRIBUTOR REPLACEMENT
(HEAVY DUTY AIR-FLOW HEATER)
(Refer to Figure 31)
The air distributor can be readily replaced
after disconnecting the attaching air hoses and the
Figure 33— Cab Outside Air Vent
" D E F R O S T " control wire,then removing the three
screws which attach distributor to dash and cowl.
HEATER CONTROL CABLE
ADJUSTMENT
Each control wire conduit is equipped with a
threaded-sleeve (fig. 32) which can be turned to
obtain full opening and closing of air doors and to
even up the heater knobs on control panel. Make
adjustment to control wire conduit if desired.
SERVICE DIAGNOSIS
The following applies to both the Standard and
Heavy Duty Air-Flow heater systems:
P O O R O R N O H E A T IN G
1. Heater hoses are kinked, deteriorated, or
switched around at the core piping.
2. Heater core plugged.
3. Poor blower motor ground connection.
4. Blower malfunctioning.
B L O W E R IN O P E R A T IV E
1. Check dash switch and blower motor con­
nections.
2. If blower operates at high speed with switch
in either " M E D . " or " S L O W " position, the speed
control resistor at top of blower shroud is defec­
tive and should be replaced. N O T E : Resistor is
attached to the blower motor scroll by two screws.
Only one-half of resistor winding maybe defective;
if so, replace the resistor assembly.
3. Check the blower motor.
VENTILATION
A single vent intake at front center of cab
cowl (fig. 33) permits outside air to enter cab
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M A N U A L