Roof Mounted System; Air Control Lever; Defroster; Fan Switch - Chevrolet 10 1971 Series Chassis Service Manual

cooler air, moving the lever toward COOL will send
some air through the evaporator core (inoperative when
the OUTLETS lever is set for heater operation) which in
effect bypasses the heater core resulting in less heat
output.

Air Control Lever

When the control is properly adjusted, full left position
("INSIDE") will supply 100% recirculated inside air, and
moving the lever to the word "OUTSIDE" will supply
100% outside air to the system.
trols a vacuum switch which in turn actuates an air inlet
door in the plenum below the air inlet grille and a recir­
culating air door in the kick pad. In the full left position,
vacuum also closes the Hot Water Shut Off Valve, pre­
venting coolant flow through the heater core.

Defroster

As the Air control knob is moved to the right from the
"OUTSIDE" position toward the word DEFROSTER the
diverter door within the distributor duct moves to send a
portion of the airflow to the defroster ducts. Full "right"
position of the AIR knob, as indicated on the panel, is the
DE-ICE position which sends the total airflow to the
defroster ducts.
Fig. 15— Four Season System Components
Lever movement con­
HEATER AND AIR CONDITIONING 1A-9

Fan Switch

The fan switch controls the operation of the three
speed blower motor.

ROOF MOUNTED SYSTEM

The Roof-Mounted System is available for CK10-20
series Suburban Carryall Trucks.
This system is similar to the Four-Season System in
placement of the compressor, condenser and receiver-
dehydrator (fig. 16). It differs from the Four-Season Sys­
tem in that it:
1. Operates independently of the heater system.
2. Operates on recirculated (inside) air only.
3. Utilizes a thermostatic switch instead of an evapora­
tor control (POA) valve to control outlet air temper­
ature.
The roof-mounted system incorporates a blower evap­
orator unit which is mounted to the inner roof panel at the
rear of the vehicle. An overhead central air distributor
duct, which contains adjustable outlets, extends forward
from the blower-evaporator unit to the windshield header
panel. The refrigerant lines are routed from the engine
compartment to the blower-evaporator unit between the
10-30 CHEVROLET TRUCK SERVICE MANUAL