B1079
B1079-CLIMATE CONTROL COOL DOWN TEST EXCESSIVE TIME (SINGLE-ZONE)
For a complete wiring diagram refer to Diagrams/Electrical.
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 13° C (55° F) and 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 13° C (55° 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.
- 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.
Diagnostic Test
1. DIAGNOSE COOLDOWN TEST STATUS MESSAGES
Were any of the following status messages present after performing the Cooldown Test?
Yes, Conditions Too Cold - Test Not Run
- If running, turn the A/C compressor off. Verify that the work area ambient temperature is above 15.6° C (60° F). If not, move the vehicle to a warmer work area. Verify that the evaporator temperature is above 13° C (55° F). If not, set the blower to high speed and allow the blower to run for five minutes. Then, run the Cooldown Test again.
Yes, Blowers Not On High - Test Not Run
- Set the blower speed to high speed and then run the Cooldown Test again.
Yes, No Results Stored/Test Not Complete
- Verify that power is not interrupted while rerunning the Cooldown Test.
No
- Go To2
2. CHECK FOR DTCs IN THE A/C HEATER CONTROL MODULE
Turn the ignition on.
With the scan tool, read HVAC DTCs.
Excluding B1079-Climate Control Cool Down Test Excessive Time, 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 3
3. CHECK FOR DTCs IN THE TIPM
With the scan tool, read TIPM DTCs.
Are any DTCs present in the TIPM?
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 4
4. CHECK FOR DTCs IN THE PCM / ECM
With the scan tool, read PCM / ECM DTCs.
Are any DTCs present in the PCM / ECM?
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
- Refer to Cooldown Test related diagnostic information and testing procedures. Rerun the Cooldown Test after the repair is complete.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test