Dodge Ram Truck 1500-2500-3500. Manual — part 2010
COOLDOWN TEST TOO COLD TO START (CONTINUED)
5.
CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT & (C121) SENSOR GROUND
CIRCUIT FUNCTION
Turn the ignition off.
Connect a jumper wire between the (C21) Evaporator Temperature
Sensor Signal circuit and the (C121) Sensor Ground circuit in the
Evaporator Temperature Sensor harness connector.
Turn the ignition on.
With the DRBIII
T
in Sensor Display, read the Evaporator Temperature
Sensor voltage.
Is the voltage below 0.10 volts?
Yes
>> Replace the Evaporator Temperature Sensor in accor-
dance with the Service Information. When the repair is
complete, start the engine, set the blower control to high
speed, and then re-run the Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8
-
ELECTRICAL/ELECTRONIC
CONTROL
MODULES/
FRONT CONTROL MODULE - DIAGNOSIS AND TEST-
ING).
No
>> Go To 6
6.
CHECK THE (C121) SENSOR GROUND CIRCUIT FOR HIGH RESISTANCE
NOTE: Ensure that the voltmeter leads are connected for positive
polarity and that they meet the terminals in the connector. Also
ensure that there is a good terminal to wire connection.
Turn the ignition off.
Remove the jumper wire from the Evaporator Temperature Sensor har-
ness connector.
Reconnect the Evaporator Temperature Sensor harness connector.
Back probe the (C121) Sensor Ground circuit between the Evaporator
Temperature Sensor harness connector and the A/C Heater Control
C1 harness connector.
Turn the ignition on.
Is the voltage below 0.10 volts?
Yes
>> Go To 7
No
>> Repair the (C121) Sensor Ground circuit for high resis-
tance. When the repair is complete, start the engine, set
the blower control to high speed, and then re-run the
Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8
-
ELECTRICAL/ELECTRONIC
CONTROL
MODULES/
FRONT
CONTROL
MODULE
-
DIAGNOSIS
AND
TESTING).
24 - 40
HVAC - ELECTRICAL DIAGNOSTICS
DR/DH
COOLDOWN TEST TOO COLD TO START (CONTINUED)
7.
CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR HIGH RESISTANCE
NOTE: Ensure that the voltmeter leads are connected for positive
polarity and that they meet the terminals in the connector. Also
ensure that there is a good terminal to wire connection.
Turn the ignition off.
Back probe the (C21) Evaporator Temperature Sensor Signal circuit
between the Evaporator Temperature Sensor harness connector and
the A/C Heater Control C1 harness connector.
Turn the ignition on.
Is the voltage below 0.10 volts?
Yes
>> Replace the A/C Heater Control in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8
-
ELECTRICAL/ELECTRONIC
CONTROL
MODULES/
FRONT CONTROL MODULE - DIAGNOSIS AND TEST-
ING).
No
>> Repair the (C21) Evaporator Temperature Sensor Signal
circuit for high resistance. When the repair is complete,
start the engine, set the blower control to high speed, and
then re-run the Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8
-
ELECTRICAL/ELECTRONIC
CONTROL
MODULES/
FRONT CONTROL MODULE - DIAGNOSIS AND TESTING).
DR/DH
HVAC - ELECTRICAL DIAGNOSTICS
24 - 41
COOLDOWN TIME EXCESSIVE FAULT
For the Manual Temperature Control circuit diagrams (Refer to 24 - HEATING & AIR CONDITIONING - SCHEMAT-
ICS AND DIAGRAMS).
For a complete wiring diagram Refer to Section 8W.
•
When Monitored:
When executing the Cooldown Test
•
Set Condition:
This message will display if the A/C system is unable to bring the evaporator temperature down 11.11°C (20°F)
within one minute.
Possible Causes
FAULTS PRESENT IN THE HVAC SYSTEM
FAULTS PRESENT IN THE POWERTRAIN SYSTEM
OTHER CONDITIONS PRESENT CAUSING A/C SYSTEM PERFORMANCE PROBLEMS
Diagnostic Test
1.
CHECK FOR DTCS IN THE A/C HEATER CONTROL
CAUTION: The work area ambient temperature must be above 21.1°C (70°F) and the evaporator temperature
must be above 12.7°C (55°F) in order to test A/C system performance.
Turn the ignition on.
With the DRBIII
T
, read HVAC DTCs.
Does the DRBIII
T
display any DTCs?
Yes
>> Diagnose and repair the DTC(s). Refer to the Table of Contents in this Section for a complete list of
HVAC related symptoms. When the repair is complete, erase the DTCs, cycle the ignition switch, start
the engine, set the blower control to high speed, and then re-run the Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/FRONT CONTROL MODULE - DIAGNOSIS AND TESTING).
No
>> Go To 2
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HVAC - ELECTRICAL DIAGNOSTICS
DR/DH
COOLDOWN TIME EXCESSIVE FAULT (CONTINUED)
2.
CHECK FOR DTCS IN THE PCM OR ECM
With the DRBIII
T
, read PCM or ECM DTCs.
Does the DRBIII
T
display any DTCs?
Yes (Gasoline Engines)
Diagnose and repair the DTC(s). (Refer to 9 - ENGINE ELECTRICAL DIAGNOSTICS). When the repair
is complete, erase the DTCs, cycle the ignition switch, start the engine, set the blower control to high
speed, and then re-run the Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/FRONT CONTROL MODULE - DIAGNOSIS AND TESTING).
Yes (Diesel Engines)
Diagnose and repair the DTC(s). (Refer to 9 - ENGINE ELECTRICAL DIAGNOSTICS). When the repair
is complete, erase the DTCs, cycle the ignition switch, start the engine, set the blower control to high
speed, and then re-run the Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/FRONT CONTROL MODULE - DIAGNOSIS AND TESTING).
No
>> Perform the A/C Performance Test. (Refer to 24 - HEATING & AIR CONDITIONING - DIAGNOSIS AND
TESTING).
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/FRONT CONTROL MODULE - DIAGNOSIS AND TESTING).
DR/DH
HVAC - ELECTRICAL DIAGNOSTICS
24 - 43
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