c. With the engine running, duct temperature
should not be less than 2° C (35° F) or than 12° C
(54° F).
(7) If the compressor has not cycled off and the
duct temperature is less than 2° C (35° F) , check the
evaporator temperature sensor and circuit by per-
forming the ATC Function Test (Refer to 24 - HEAT-
ING & AIR CONDITIONING - DIAGNOSIS AND
TESTING).
(8) If duct output temperature is not within speci-
fications, check the refrigerant system for leaks and
proper refrigerant charge (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - DIAGNOSIS
AND TESTING) and (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - STANDARD PRO-
CEDURE).
DIAGNOSIS AND TESTING - HEATER
PERFORMANCE
Before performing the following tests, perform the
ATC Function Test using the DRBIIIt and refer to
Cooling for the procedures to check the radiator cool-
ant level, serpentine drive belt tension, radiator air
flow and the radiator fan operation.
MAXIMUM HEATER OUTPUT
Engine coolant is provided to the heater core
through a heater valve and heater hose. With the
engine idling at normal operating temperature, set
the heater-A/C controls as follows:
• Temperature control in the full hot position
• Mode control in the floor heat position
• Blower motor control in the highest speed posi-
tion
Using a test thermometer, check the temperature
of the air being discharged at the floor outlets. Com-
pare the test thermometer reading to the Tempera-
ture Reference chart.
TEMPERATURE REFERENCE CHART
Ambient Temperature Minimum Floor Outlet Temperature
Celsius Fahreheit Celsius Fahreheit
15.5° 60° 62.2° 144°
21.1° 70° 63.8° 147°
26.6° 80° 65.5° 150°
32.2° 90° 67.2° 153°
If the floor outlet air temperature is insufficient,
check for a faulty heater valve (perform ATC Func-
tion Test) and verify that the cooling system is oper-
ating to specifications (Refer to 7 - COOLING/
ENGINE/COOLANT - DIAGNOSIS AND TESTING).
Both of the heater hoses should be HOT to the touch
(the coolant return heater hose should be slightly
cooler than the supply hose. If the coolant return
hose is much cooler than the supply hose, locate and
repair the engine coolant flow obstruction in the
heater system.
POSSIBLE LOCATIONS OR CAUSE OF
OBSTRUCTED COOLANT FLOW
• Pinched or kinked heater hoses.
• Improper heater hose routing.
• Plugged heater hoses or supply and return ports
at the cooling system connections.
• Inoperative or stuck heater water valve.
• Plugged heater core.
If proper coolant flow is verified, and heater floor
outlet air temperature is insufficient, a mechanical
problem may exist.
POSSIBLE LOCATIONS OR CAUSE OF
INSUFFICIENT HEAT
• An obstructed cowl air intake.
• Obstructed heater system outlets.
• Heater water valve not functioning properly.
TEMPERATURE CONTROL
If outlet air temperature cannot be adjusted with
the A/C-heater temperature control, one of the follow-
ing could require service:
• Faulty A/C-heater control switch.
• Faulty temperature sensor.
• Faulty A/C-heater control cable or actuator.
• Faulty A/C-heater control module.
24 - 4 HEATING & AIR CONDITIONING VA
HEATING & AIR CONDITIONING (Continued)
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