B1079–CLIMATE CONTROL COOL DOWN TEST EXCESSIVE TIME
For a complete wiring diagram Refer to Section 8W.
Theory of Operation
The Cooldown Test checks A/C system performance based on Evaporator Temperature Sensor input. The main cri-
teria is to lower evaporator temperature 11.11°C (20°F) within one minute. Before starting the test, the evaporator
temperature must be above 18.3°C (65°F) and the blower speed must be set to high speed. When the test is run-
ning, A/C Select and A/C Request will be on and the A/C status indicator will flash. When the test is complete, the
scan tool will display one or more test status messages to indicate the outcome of the Cooldown Test. A Successful
Cooldown – Test Passed status message indicates that the main test criteria was met. A DTC Set During Routine
– Test Not Passed status message indicates that the A/C system is unable to lower the evaporator temperature
11.11°C (20°F) within one minute. A Conditions Too Cold – Test Not Run status message indicates that the evap-
orator temperature was below 18.3°C (65°F) when starting the Cooldown Test. A Blowers Not On High – Test Not
Run status message indicates that either the blower speed was not set to high speed prior to starting the Cooldown
Test or the blower speed was changed from high speed to another setting after starting the Cooldown test. A Refrig-
erant Temperature Sensor Error status message indicates that a fault occurred with the Evaporator Temperature
Sensor/sensor circuits. A No Results Stored/Test Not Complete status message indicates that the power was cycled
while the test was running.
•
When Monitored:
When the Cooldown Test is executed.
•
Set Condition:
If the A/C system is unable to lower the evaporator temperature 11.11°C (20°F) within one minute.
Possible Causes
EVAPORATOR TEMPERATURE SENSOR CIRCUITS
EVAPORATOR TEMPERATURE SENSOR
OTHER HVAC SYSTEM FAULTS PRESENT SUCH AS INSUFFICIENT REFRIGERANT CHARGE
POWERTRAIN SYSTEM FAULTS PRESENT
Diagnostic Test
1.
CHECK FOR DTCs IN THE A/C HEATER CONTROL MODULE
Turn the ignition on.
With the scan tool, select ECU View.
With the scan tool, select HVAC.
Are any DTCs present in the A/C Heater Control Module?
Yes
>> Diagnose and Repair the DTC(s). Refer to the Table of Contents in this Section for a complete list of
HVAC related symptoms. Run the Cooldown Test again after the repair is complete.
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
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