Page 544 of 4284

BLEND OVERCURRENT (STORED) - MANUAL A/C
When Monitored: When actuator movement is requested.
Set Condition: All (Blend, Mode, Recirc, and Zone) Overcurrent DTCs will set if the A/C
- Heater Control Module detects an excessive current draw on the Common Door Drive
circuit(s).
CHECKSUM FAILURE (STORED) - MANUAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the calibrated check sum does not match the stored
value.
EVAPORATOR TEMPERATURE SENSOR CIRCUIT OPEN (STORED) - MANUAL
A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the Evaporator Temperature Sensor/sensor circuit is
open.
EVAPORATOR TEMPERATURE SENSOR CIRCUIT SHORT (STORED) - MAN-
UAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the Evaporator Temperature Sensor/sensor circuit is
shorted low.
LOOPBACK FAILURE (STORED) - MANUAL A/C
When Monitored: When the A/C - Heater Control Module executes an internal loopback
test.
Set Condition: If the A/C - Heater Control Module fails to send a message, or none of the
expected messages arrive for 5 seconds, an internal loopback test is executed. If the
internal loopback test fails, the DTC will set.
LOOPBACK TEST FAILURE (STORED) - MANUAL A/C
When Monitored: When the A/C - Heater Control Module executes an internal loopback
test.
Set Condition: If the A/C - Heater Control Module fails to send a message, or none of the
expected messages arrive for 5 seconds, an internal loopback test is executed. If the
internal loopback test fails, the DTC will set.
MODE OVERCURRENT (STORED) - MANUAL A/C
When Monitored: When actuator movement is requested.
Set Condition: All (Blend, Mode, Recirc, and Zone) Overcurrent DTCs will set if the A/C
- Heater Control Module detects an excessive current draw on the Common Door Drive
circuit(s).
515
HEATING & A/C
A/C FAULT (STORED) - MANUAL A/C ÐContinued
Page 561 of 4284

Symptom List:
COOLDOWN TEST EXCESSIVE FAULT - MANUAL A/C
COOLDOWN TEST SENSOR FAILURE - MANUAL A/C
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be COOLDOWN TEST EXCESSIVE
FAULT - MANUAL A/C.
When Monitored and Set Condition:
COOLDOWN TEST EXCESSIVE FAULT - MANUAL A/C
When Monitored: When executing the Cooldown Test.
Set Condition: This message will be displayed if the A/C system is unable to bring the
evaporator temperature down -6.7ÉC (20ÉF) within two minutes.
COOLDOWN TEST SENSOR FAILURE - MANUAL A/C
When Monitored: When executing the Cooldown Test.
Set Condition: This message will be displayed if a fault is detected with the Evaporator
Temperature Sensor/circuit when executing the Cooldown Test.
POSSIBLE CAUSES
HVAC DTC(S) PRESENT
CHECK THE PCM/ECM FOR DTCS
A/C SYSTEM TESTING
TEST ACTION APPLICABILITY
1CAUTION: The evaporator temperature must be above 12.7ÉC (55ÉF) to test
A/C system operation.
Turn the ignition on.
With the DRBIIIt, read HVAC DTCs.
Does the DRBIIItdisplay any HVAC DTCs?All
Ye s®Return to the symptom list and choose the symptoms(s).
After repair is complete, rerun the Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 2
532
HEATING & A/C
Page 564 of 4284

Symptom:
COOLDOWN TEST TOO COLD TO START - MANUAL A/C
When Monitored and Set Condition:
COOLDOWN TEST TOO COLD TO START - MANUAL A/C
When Monitored: When executing the Cooldown Test.
Set Condition: This message will be displayed if the A/C - Heater Control Module sees
evaporator temperature below 12.7ÉC (55ÉF) when executing the Cooldown Test.
POSSIBLE CAUSES
EVAPORATOR TEMPERATURE TOO LOW
HVAC DTC(S) PRESENT
CHECK THE PCM/ECM FOR DTCS
EVAPORATOR TEMPERATURE SENSOR
SENSOR GROUND CIRCUIT HIGH RESISTANCE
EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT HIGH RESISTANCE
A/C - HEATER CONTROL MODULE
TEST ACTION APPLICABILITY
1CAUTION: The work area ambient temperature must be above 15.6ÉC (60ÉF)
to test A/C system operation.
Start the engine.
Turn the A/C off.
Turn the Blower on high. Allow the blower to run for 5 minutes to ensure that the
Evaporator Temperature Sensor temperature is above 12.7ÉC (55ÉF).
With the DRBIIIt, actuate the Cooldown Test.
Does the DRBIIItdisplay: Cooldown Test Too Cold To Start?All
Ye s®Go To 2
No®Perform additional testing as necessary.
Perform BODY VERIFICATION TEST - VER 1.
2CAUTION: The work area ambient temperature must be above 15.6ÉC (60ÉF)
to test A/C system operation.
Turn the ignition on.
With the DRBIIIt, read HVAC DTCs.
Does the DRBIIItdisplay any HVAC DTCs?All
Ye s®Return to the symptom list and choose the symptom(s). After the
repair is complete, with the DRBIIIt, erase the DTC(s). Cycle the
ignition switch. With the DRBIIIt, actuate the Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 3
535
HEATING & A/C
Page 565 of 4284

TEST ACTION APPLICABILITY
3CAUTION: The work area ambient temperature must be above 15.6ÉC (60ÉF)
to test A/C system operation.
Turn the ignition on.
With the DRBIIIt, check the PCM/ECM for DTCs.
Are any DTCs present?All
Ye s®Refer to Powertrain Diagnostic information for the related symp-
tom(s). After the repair is complete, with the DRBIIIt, erase the
DTC(s). Cycle the ignition switch. With the DRBIIIt, actuate the
Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 4
4 Turn the ignition off.
Disconnect the Evaporator Temperature Sensor harness connector.
Turn the ignition on.
With the DRBIIItin Sensor Display, read the Evaporator Temperature Sensor
voltage.
Is the voltage above 4.9 volts?All
Ye s®Go To 5
No®Go To 6
5 Turn the ignition off.
Disconnect the Evaporator Temperature Sensor harness connector.
Connect a jumper wire between the Evaporator Temperature Sensor Signal circuit
and the Sensor Ground circuit at the Evaporator Temperature Sensor harness
connector.
Turn the ignition on.
With the DRBIIItin Sensor Display, read the Evaporator Temperature Sensor
voltage.
Is the voltage 0.0 volts?All
Ye s®Replace the Evaporator Temperature Sensor in accordance with
the Service Information. After repair is complete, rerun the
Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 6
6NOTE: Ensure that the voltmeter leads meet the terminals in the connector
and that there is good terminal to wire connection.
NOTE: Ensure the voltmeter leads are connected for positive polarity.
Back probe the Sensor Ground circuit between the Evaporator Temperature Sensor
harness connector and the A/C - Heater Control Module C1 harness connector.
Turn the ignition on.
Is the voltage below 0.10 volt?All
Ye s®Go To 7
No®Repair the high resistance in the Sensor Ground circuit. After
repair is complete, rerun the Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1.
536
HEATING & A/C
COOLDOWN TEST TOO COLD TO START - MANUAL A/C ÐContinued
Page 566 of 4284
TEST ACTION APPLICABILITY
7NOTE: Ensure the voltmeter leads meet the terminals in the connector and
that there is good terminal to wire connection.
NOTE: Ensure the voltmeter leads are connected for positive polarity
Back probe the Evaporator Temperature Sensor Signal circuit between the Evapo-
rator Temperature Sensor harness connector and the A/C - Heater Control Module C1
harness connector.
Turn the ignition on.
Is the voltage below 0.10 volt?All
Ye s®Replace the A/C - Heater Control Module in accordance with the
Service Information. After repair is complete, rerun the Cooldown
Test.
Perform BODY VERIFICATION TEST - VER 1.
No®Repair the high resistance in the Evaporator Temperature Sensor
Signal circuit. After repair is complete, rerun the Cooldown Test.
Perform BODY VERIFICATION TEST - VER 1.
537
HEATING & A/C
COOLDOWN TEST TOO COLD TO START - MANUAL A/C ÐContinued
Page 567 of 4284

Symptom:
EVAPORATOR TEMPERATURE SENSOR CIRCUIT OPEN (ACTIVE)
- MANUAL A/C
When Monitored and Set Condition:
EVAPORATOR TEMPERATURE SENSOR CIRCUIT OPEN (ACTIVE) - MANUAL
A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the Evaporator Temperature Sensor/sensor circuit is
open.
POSSIBLE CAUSES
EVAPORATOR TEMPERATURE SENSOR
EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT OPEN
SENSOR GROUND CIRCUIT OPEN
A/C - HEATER CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Open the glove box door. Disconnect the glove box door roller latch from each side of
the glove box. Roll the glove box downward toward the floor.
Disconnect the in-line C202 harness connector.
Connect a jumper wire between the Evaporator Temperature Sensor Signal circuit
and the Sensor Ground circuit at the in-line C202 harness connector (HVAC side).
Turn the ignition on.
With the DRBIIItin Sensor Display, read the Evaporator Temperature Sensor
voltage.
Does the DRBIIItdisplay: 0.0 volts?All
Ye s®Check the wiring harness between the in-line C202 harness
connector (plenum side) and the Evap Temp Sensor for an open.
Repair as necessary. If Ok, replace the Evaporator Temperature
Sensor in accordance with the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 2
538
HEATING & A/C
Page 568 of 4284

TEST ACTION APPLICABILITY
2 Turn the ignition off.
Disconnect the A/C - Heater Control Module C1 harness connector.
Open the glove box door. Disconnect the glove box door roller latch from each side of
the glove box. Roll the glove box downward toward the floor.
Disconnect the in-line C202 harness connector.
Measure the resistance of the Evaporator Temperature Sensor Signal circuit between
the A/C - Heater Control Module C1 harness connector and the in-line C202 harness
connector.
Is the resistance below 5.0 ohms?All
Ye s®Go To 3
No®Repair the Evaporator Temperature Sensor Signal circuit be-
tween the A/C - Heater Control Module C1 harness connector and
the in-line C202 harness connector (HVAC side) for an open.
Perform BODY VERIFICATION TEST - VER 1.
3 Turn the ignition off.
Disconnect the A/C - Heater Control Module C1 harness connector.
Open the glove box door. Disconnect the glove box door roller latch from each side of
the glove box. Roll the glove box downward toward the floor.
Disconnect the in-line C202 harness connector.
Measure the resistance of the Sensor Ground circuit between the A/C - Heater
Control Module C1 harness connector and the in-line C202 harness connector.
Is the resistance below 5.0 ohms?All
Ye s®Replace the A/C - Heater Control Module in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No®Repair the Sensor Ground circuit between the A/C - Heater
Control Module C1 harness connector and the in-line C202
harness connector (HVAC side) for an open.
Perform BODY VERIFICATION TEST - VER 1.
539
HEATING & A/C
EVAPORATOR TEMPERATURE SENSOR CIRCUIT OPEN (ACTIVE) -
MANUAL A/C Ð
Continued
Page 569 of 4284

Symptom:
EVAPORATOR TEMPERATURE SENSOR CIRCUIT SHORT (AC-
TIVE) - MANUAL A/C
When Monitored and Set Condition:
EVAPORATOR TEMPERATURE SENSOR CIRCUIT SHORT (ACTIVE) - MANUAL
A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the Evaporator Temperature Sensor/sensor circuit is
shorted low.
POSSIBLE CAUSES
EVAPORATOR TEMPERATURE SENSOR
EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT SHORT TO GROUND
EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT SHORT TO SENSOR GROUND CIR-
CUIT
A/C - HEATER CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Open the glove box door. Disconnect the glove box door roller latch from each side of
the glove box. Roll the glove box downward toward the floor.
Disconnect the in-line C202 harness connector.
Turn the ignition on.
With the DRBIIItin Sensor Display, read the Evaporator Temperature Sensor
voltage.
Does the DRBIIItdisplay: 5.0 volts or greater?All
Ye s®Check the Evap Temp Sensor Signal circuit between the in-line
C202 harness connector (plenum side) and the Evap Temp Sensor
for a short to ground. Repair as necessary. If Ok, replace the
Evaporator Temperature Sensor in accordance with the Service
Info.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 2
540
HEATING & A/C