GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 CTS - RHD 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Too Cold in Vehicle

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The temperature cannot be adjusted, or heating is insufficient.

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

Place the blower motor switch in each speed position.

Does the blower motor operate in any speed position?

--

Go to Step 3

Go to Blower Motor Inoperative

3

Does the blower motor operate at the desired speeds?

--

Go to Step 4

Go to Blower Motor Malfunction

4
  1. Start the engine
  2. Observe the coolant bypass valve

Does the coolant bypass valve move to the engine block flow position?

--

Go to Step 5

Go to Coolant Bypass Valve Inoperative

5
  1. Install a scan tool
  2. Turn on the ignition with the engine off
  3. With a scan tool, command the water pump control ON in the climate control panel special functions, miscellaneous test.

Does the after boil coolant pump operate?

--

Go to Step 6

Go to After Boil Coolant Pump Inoperative

6
  1. Start the engine.
  2. Place the mode switch in the panel position.
  3. Place the recirculation switch in the ON position.
  4. Observe the recirculation door.
  5. Place the recirculation switch in the OFF position.

Does the recirculation door move from the recirculation position to the outside air position?

--

Go to Step 7

Go to Air Recirculation Malfunction

7

Place the passenger temperature switch in the OFF position.

Does the Too Cold in vehicle condition occur when heating or defrosting is desired?

--

Go to Step 8

Go to Step 10

8
  1. Start the engine.
  2. Turn OFF the HVAC controls.

Does the A/C compressor operate?

--

Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 9

9

Inspect the cooling system for the following conditions:

    • A low coolant level
    • A loose or worn accessory drive belt
    • A leaking radiator hose or heater hose
    • A kinked radiator hose or heater hose
    • A missing radiator cap pressure seal
    • A leaking radiator cap

Refer to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 10

10

Place the mode switch in panel position.

Turn ON the ignition with the engine OFF.

Place the blower motor switch in maximum speed position.

Inspect for airflow through the inside air temperature sensor by placing a 5 cm (2 in) square piece of paper over the sensor air inlet.

Does the paper stay in place?

--

Go to Step 11

Go to Step 17

11
  1. Install a thermometer near the inside air temperature sensor.
  2. With a scan tool, observe the Inside Air Temp parameter in the Climate Control Panel data list.

Does the scan tool indicate the sensor temperatures is within 3°C (5°F) of the thermometer temperature?

--

Go to Step 12

Go to Step 15

12
  1. Turn OFF the ignition.
  2. Cover the sunload sensor.
  3. Turn ON the ignition.
  4. With a scan tool, observe the Driver and Passenger Solar Sensor parameter in the Climate Control Panel Open/Short data list.

Is the Solar Sensor parameter greater than the specified value?

220 Counts

Go to Step 13

Go to Step 20

13
  1. Uncover the sunload sensor.
  2. Direct a light source at the sunload sensor.
  3. Observe the Driver and Passenger Sunload parameter.

Do the counts change?

--

Go to Step 14

Go to Step 20

14

Test the resistance of the ambient air temperature sensor. Refer to Sensor Resistance Table .

Is the resistance near the value in the Sensor Resistance Table?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 16

15

Test the resistance of the inside air temperature sensor. Refer to Sensor Resistance Table .

Is the resistance near the value in the Sensor Resistance Table?

--

Go to Step 21

Go to Step 19

16

Inspect for poor connections at the harness connector of the ambient air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 18

17

Inspect the aspirator tube for a air leak or obstruction.

Did you find and correct the condition?

--

Go to Step 26

--

18

Inspect for poor connections at the harness connector of the ambient air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 24

19

Inspect for poor connections at the harness connector of the inside air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 22

20

Inspect for poor connections at the harness connector of the sunload sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 23

21

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 in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 25

22

Replace the inside air temperature sensor. Refer to Inside Air Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 26

--

23

Replace the sunload sensor. Refer to Sun Load Sensor Replacement .

Did you complete the replacement?

--

Go to Step 26

--

24

Replace the ambient air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 26

--

25

Replace the HVAC Control Module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

--

Go to Step 26

--

26

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2