Chrysler DODGE D150 1993 Service Manual page 1440

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HEATING AND AIR CONDITIONING 24 - 3
D I A G N O S T I C P R O C E D U R E S
INDEX
page page
. . 7 General Information 3
. . 3 Heating System Output 3
Air Conditioning System
Blower Motor
GENERAL INFORMATION
The reason for owner dissatisfaction must be thor­
oughly understood before any attempt is made to re­
pair or replace any parts. It must be determined if
the condition is the heater system, the refrigerant
system, air conditioning air flow or related to the
compressor. After confirming the condition, a func­
tional test is suggested using the diagnostic charts.
After the condition has been properly diagnosed and
corrected, check out the complete system to assure
that it is performing satisfactorily.
The following charts have been developed for quick
reference. If the step by step method used is not com­
pletely understood, refer to the correct section of the
Service Manual for detailed explanations.
HEATING SYSTEM OUTPUT
W A R N I N G : IF V E H I C L E H A S B E E N R U N R E C E N T L Y ,
WAIT 15 M I N U T E S B E F O R E R E M O V I N G C A P , T H E N
P L A C E A R A G O V E R T H E C A P A N D T U R N IT T O
T H E F I R S T S T O P . A L L O W P R E S S U R E TO E S C A P E
T H R O U G H T H E O V E R F L O W T U B E AND W H E N T H E
S Y S T E M S T A B I L I Z E S , R E M O V E T H E C A P C O M ­
P L E T E L Y .
Check the radiator coolant level, drive belt tension,
engine vacuum line connections, radiator air flow
and radiator fan operation. Start engine and bring to
normal operating temperature (refer to Group 7,
Cooling System).
Engine coolant is provided to the heater system by
2 heater hoses. With engine idling at normal operat­
ing temperature, set the heater control to maximum
heat, defrost and high blower setting. Using a test
thermometer, check the air temperature coming from
the defroster outlets (refer to Temperature Reference
Chart).
Should the temperature not meet the minimum
values shown, refer to Heater Diagnosis (Mechanical)
for possible causes and corrections.
(1) Remove radiator pressure cap.
(2) Drain 1 pint of coolant from the radiator.
(3) Warm the engine to operating temperature by
idling for 20 minutes, with the pressure cap off. Idle
longer if working outdoors in cold temperatures.
(4) With the engine idling, place a thermometer
into the coolant in the radiator filler neck.
TEMPERATURE REFERENCE CHART
AMBIENT
MINIMUM HEATER SYSTEM
TEMPERATURE AIR OUTLET TEMPERATURE
°C °F °C
°F
15.5
60 62.2 144
21.1
70 63.8
147
26.6 80 65.5 150
32.2 90 67.2
153
J9124-11
(5) Engine coolant temperature should stabilize at
no lower than 86°C (187°F) or 4°C (8°F) below the
thermostat opening temperature. This should happen
during the vehicle operating cycle.
(6) Instrument panel control in HEAT mode.
(7) Set to high blower speed.
(8) Temperature lever to maximum heat position.
BLOWER MOTOR
The heater control blower speed selector switch and
resistor block supplies the blower motor with voltage.
A varied voltage is supplied for low and middle
speeds while battery voltage is supplied for high
speed (Fig. 1).
Fig. 1 Blower Motor Resistor Block (Typical)
Refer to Heater Blower Motor/Control System Di­
agnosis (Electrical) Chart and Blower Motor Noise/
Vibration Chart.