Conditions

No/Inefficient Heating

Fault symptoms
No/inefficient heating

Diagnostic help
On certain markets, cars are equipped with a vacuum-operated shut-off valve for the heat exchanger. Certain cars are equipped with electric circulation pump.

Check that there are no impurities in the coolant.

Check and reset any user programming of the ACC.





Diagnostic procedure

1. Calibrating the control panel
^ Turn the ignition key to ON.





^ Calibrate the control panel.





^ Contact the ACC.





^ Read diagnostic trouble codes from: ACC.

Are there any diagnostic trouble codes?
YES
^ If there are any diagnostic trouble codes, see "Electronic Climate Control, Testing and Inspection." for the codes in question. Testing and Inspection

NO
^ Go to step 2.

2. Checking the shut-off valve, heat exchanger present
^ Check if the car is equipped with a shut-off valve for the heat exchanger.

Is the car equipped with a shut-off valve for the heat exchanger?
YES
^ Go to step 3.
NO
^ Go to step 4.

3. Checking the function of the shut-off valve
^ Check the function of the heat exchanger shut- off valve.

Is the valve letting through water as it should?
YES
^ Go to step 4.
NO
^ Rectify the fault.

4. Check if there is a circulation pump
^ Check if the car is equipped with a circulation pump.

Is the car equipped with a circulation pump?
YES
^ Go to step 5.
NO
^ Go to step 6.

5. Checking the function of the circulation pump
^ Check the function of the circulation pump.

Is the function correct?
YES
^ Go to step 6.
NO
^ Rectify the fault.





6. Checking engine temperature
^ Start the engine and let it run until the thermostat opens.





^ Connect the diagnostic tool and read Engine temperature in Trionic.

Is the temperature correct according to the specification in section Technical Data?
YES
^ The engine coolant system is functioning correctly.
NO
^ Rectify the fault.