Subject Page; 1A-2 Heating; R/V And G Series Heaters - Description; Blower And Air Inlet Assembly - GMC G Service Manual

1A-2 HEATING

SUBJECT
G>Van Auxiliary Heater............................................................................................................................................. 1A-23
Description............................................................................................................................................................. 1A-23
G-Van Auxiliary Heater - On-Vehicle Service...................................................................................................... 1A-26
Blower Motor Replacement.................................................................................................................................. 1A-26
Heater Core Replacement..................................................................................................................................... 1A-26
Coolant-Control Valve Replacement....................................................................................................................1A-26
Resistor Replacement........................................................................................................................................... 1A-26
Specifications............................................................................................................................................................ 1A-27

R/V AND G SERIES HEATERS - DESCRIPTION

Heating components are attached to the right side of the
cowl. The blower and air inlet assembly and water hoses
are located on the forward side of the cowl panel while the
heater core and distributor duct are on the passenger side.
The heater system is an air-mix type system in which
outside air is heated and then mixed in varying amounts
with cooler outside air to attain the desired air temperature.
The system consists of (1) a blower and air inlet assembly,
(2) a heater distributor assembly and (3) a heater control
assembly.
BLOWER AND AIR
INLET ASSEMBLY
The blower and air inlet assembly draws outside air
through the outside air inlet grille located forward of the
windshield reveal molding and channels the air into the
heater distributor assembly. The operation of the blower
motor is controlled by the fan switch on the heater control.
The motor is connected in series with the fan switch and the
blower resistor assembly.
CONTENTS (Cont'd)

HEATER DISTRIBUTOR ASSEMBLY

The heater distributor assembly houses the heater core
and the doors necessary to control mixing and channeling
of the air. Since the unit has no water valve, water circula­
tion keeps the core hot at all times. That portion of the air
passing through the core receives maximum heat from the
core. Air entering the distributor assembly is channeled as
follows:
Air entering the distributor can be directed out the purge
door opening on the right end of the distributor assembly by
the temperature door. If the temperature door is closed, air
is directed around the heater core; if it is open or partially
open, air is directed through the heater core and heated. Air
is then directed into the passenger compartment through
the heater (floor) outlets and/or the defroster (dash) outlets
by the defroster door. The temperature of the outlet air is
dependent on the ratio of heated to unheated air (controlled
by the temperature door).
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