1. Air inlet box
2. Cooling unit
3. Heater unit
4. Heater core
5. Supplementary heater
6. A / C evaporator and
expansion valve
7. Fresh air
8. Recirculation air
9. Ventilation air
10. Demister air
11. Foot air
12. Defroster air
1A-2
HEATER AND VENTILATION
GENERAL DESCRIPTION
SUPPLEMENTARY HEATER
The supplementary heater which is operated by electricity is located in the heater unit near by the conventional
type heater core and adds more heat to the air.
The supplementary heater is designed to be turned off while the radiator fan is in operation even though the supple-
mentary heater switch is in ON position by triggering the radiator fan signal relay.
DIAGNOSIS
DIAGNOSIS TABLE
Condition
Possible cause
Inspection / correction
Supplementary heater won’t
operate with its switch ON
D
Fuses blown
D
Supplementary heater switch
faulty
D
Supplementary heater relay faulty
D
Radiator fan signal relay faulty
Check for short circuit to ground
and replace fuses.
Check supplementary heater
switch.
Check supplementary heater
relay.
Check radiator fan signal relay
D
Radiator fan signal relay faulty
D
Supplementary heater faulty
D
Blower motor switch faulty
D
Indicator lamp burn out
Check radiator fan signal relay.
Check supplementary heater.
Check blower motor switch. (Refer
to HEATER CONTROL LEVER
ASSEMBLY in this section)
Repair supplementary heater
switch
Supplementary heater won’t turn
OFF when radiator or condenser
fan are in operation (But switch
remain ON)
D
Radiator fan signal relay faulty
D
Wiring or grounding faulty
Check radiator fan signal relay.
Check “Lg” circuit, “B” circuit and
grounding.