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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 13 (HVAC System - Automatic) >> Diagnostic Information and Procedures >> Too Hot in Vehicle - Auxiliary >> Test Description

Test Description

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 3:  This test resets the HVAC control module and checks for current air temperature actuator DTC.
  2. 7:  The specified values are from the A/C System Performance Test.
Too Hot in Vehicle - Auxiliary

Step Action Values Yes No
Schematic Reference: HVAC Schematics 
Connector End View Reference: HVAC Connector End Views 
DEFINITION: The auxiliary air temperature cannot be adjusted from one or both auxiliary controls, or the auxiliary cooling is insufficient.
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 The auxiliary HVAC control module cannot request A/C compressor operation. An A/C request must be generated by the HVAC control module to provide cooled airflow through the auxiliary system.
Does the HVAC control module operate and provide sufficient heating?
- Go to Step 3  Go to Too Cold in Vehicle 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the current DTC list in HVAC Module using the scan tool.
Does the scan tool display DTC B0428 or B0429?
- Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Step 4 
4 Place the auxiliary blower motor switch in each speed position.
Does the auxiliary blower motor operate in each speed position?
- Go to Step 5  Go to Auxiliary Blower Motor Malfunction 
5 Does the auxiliary blower motor operate at the desired speeds? - Go to Step 6  Go to Auxiliary Blower Motor Malfunction 
6 Does the Too Hot In Vehicle concern occur when A/C is desired? - Go to Step 7  Go to Step 8 
Perform the A/C system performance test. Refer to Air Conditioning (A/C) System Performance Test .
Did you find and correct the condition?
- Go to Step 19  Go to Step 8 
8
  1. Place the auxiliary air temperature switch from the coldest position to the warmest position.
  2. Observe the Rear Temp Dr. offset parameter in the Rear Climate Control Panel.
Does the scan tool indicate that the value of the Rear Temp Dr. offset parameter changes from the minimum specified value to the maximum specified value?
-4 to +4 Go to Step 9  Go to Step 13 
9
  1. Observe the Rear Temp Dr. Actual parameter in the Instrument Panel Module.
  2. Place the left air temperature switch of the front HVAC control module from the coldest to the warmest position.
Does the scan tool indicate that the value of the Rear Temp Dr. Actual parameter changes from the minimum specified value to the maximum specified value?
0-255 counts Go to Step 10  Go to Step 15 
10 Inspect the auxiliary air temperature sensor for the following conditions.
  • An obstruction to the airflow
  • A damaged or a missing seal to the sensor
  • Misaligned air ducts
  • A misaligned sensor

Did you find and correct the condition?
- Go to Step 19  Go to Step 11 
11
  1. Install a thermometer near the auxiliary air temperature sensor.
  2. With a scan tool, observe the Rear Duct Temp data parameters in the HVAC Module Sensors Data list.
Does the scan tool indicate that the sensor temperatures are within the specification at the thermometer temperatures?
-3 to +3°C (-5 to +5°F) Go to Step 19  Go to Step 12 
12 Test the temperature sensor resistance. Refer to Sensor Resistance Table  table..
Does the resistance measure near the Sensor Resistance Table value?
- Go to Step 16  Go to Step 14 
13 Inspect for poor connections at the harness connector of the auxiliary HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
- Go to Step 19  Go to Step 17 
14 Inspect for poor connections at the harness connector of the auxiliary air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
- Go to Step 19  Go to Step 16 
15 Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
- Go to Step 19  Go to Step 18 
16 Replace the air temperature sensor. Refer to Inside Air Temperature Sensor Assembly Replacement .
Did you complete the replacement?
- Go to Step 19  -
17 Replace the auxiliary HVAC control module. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?
- Go to Step 19  -
18 Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?
- Go to Step 19  -
19 Operate the system in order to verify the repair.
Did you correct the condition?
- System OK Go to Step 2