B1079

B1079-CLIMATE CONTROL COOL DOWN TEST EXCESSIVE TIME (ATC & MTC)

For a complete wiring diagram refer to Wiring Section.

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
- Powertrain system faults present

Theory of Operation
The Cooldown Test checks A/C system performance based on Evaporator Temperature Sensor input. The main criteria 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 for Manual Temperature Control systems the front blower speed must be set to high speed. When the test is running, 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 evaporator 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 front blower speed was not set to high speed prior to starting the Cooldown Test or the front blower speed was changed from high speed to another setting after starting the Cooldown test. A Refrigerant 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.

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.

Q: Are any DTCs present in the A/C Heater Control Module?

YES: Diagnose and Repair the DTC(s). Rerun the Cooldown Test after the repair is complete. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 2

2. CHECK FOR DTCs IN THE PCM
With the scan tool, select PCM.

Q: Are any DTCs present in the PCM?

YES: Diagnose and repair the DTC(s). Rerun the Cooldown Test after the repair is complete. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Return the Cooldown Test after the repair is complete. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test