HEATING OUTPUT AND TEMPERATURE DOOR ACTIVATION, CHECKING, "Convenience" VERSION: Notes

Test requirements are met. Refer to HEATING OUTPUT AND TEMPERATURE DOOR ACTIVATION, TESTING REQUIREMENTS .

-- Close the engine hood.

-- Close the doors, the windows, the sunroof and the rear lid.

-- Open all instrument panel vents.

-- Turn on the ignition and activate the ready mode, the engine start by itself if needed (high voltage vehicles).

-- Start the engine (not high voltage vehicles).

Set the following on the Climatronic Control Module -J255- A/C display and control head:

• "Auto" for the driver and passenger side (the indicator lamp in the AUTO  buttons come on).
• Temperature preset for the driver and front passenger side set to "cold" ("LO" in the Climatronic Control Module -J255- or in the MMI display).
• A/C compressor is turned on (the indicator lamp in the AC  or A/C  button turns on).
• Preset for the fresh air blower "maximum speed" (in the Climatronic Control Module -J255- display and in the MMI display, setting "10" or greater).
• Set the airflow direction using the knob on the A/C display and control head for the driver and passenger side to "footwell" and "instrument panel vents" (in the Climatronic Control Module -J255- and in the MMI display)

-- Set the Rear Temperature Selection Potentiometer -G538- to "cold" (installed in the rear center console vent).

-- Open the vents in the rear center console.

-- Initiate the Guided Fault Finding for the A/C system and select the "Read measuring value block" function, using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.

-- Let the A/C system run several minutes at maximum cooling output (A/C compressor is switched on, indicator lamp in the AC  or A/C  button comes on).

-- Compare the Evaporator Vent Temperature Sensor -G263- measured value with the measured values of the Left Front Upper Body Vent Temperature Sensor -G385-, the Right Front Upper Body Vent Temperature Sensor -G386-, the Left Footwell Vent Temperature Sensor -G261- and the Right Footwell Vent Temperature Sensor -G262-).

Specified values: 

• The measured values of the temperature sensor after heat exchanger (Left Front Upper Body Vent Temperature Sensor -G385-, Right Front Upper Body Vent Temperature Sensor -G386-, Left Footwell Vent Temperature Sensor -G261- and Right Footwell Vent Temperature Sensor -G262-) may be a maximum of 5 °C (41 °F) greater than the value of the Evaporator Vent Temperature Sensor -G263- after five minutes.

If the required values are not reached, perform a fault finding at a temperature increase on the evaporator. Refer to TEMPERATURE INCREASE DOWNSTREAM FROM EVAPORATOR, DETERMINING MALFUNCTION . .

-- Using a commercially available thermometer, measure the air coming out of the vents in the rear center console and the rear footwell vents (left and right under the front seats) and compare the measured values with the temperatures displayed in the measured values block.

Specified values: 

• The measured values may be 5 °C (41 °F) greater than the displayed measured values for the temperature sensor.

If the required values are not reached, perform a fault finding at a temperature increase on the evaporator. Refer to TEMPERATURE INCREASE DOWNSTREAM FROM EVAPORATOR, DETERMINING MALFUNCTION .

-- Using the knob on the Climatronic Control Module -J255- A/C display and control head, select the "warm" temperature setting for the front passenger side ("HI" in the Climatronic Control Module -J255- and in the MMI display).

-- Read the measured values displayed for the temperature sensor in the measured value block (Evaporator Vent Temperature Sensor -G263-, Left Front Upper Body Vent Temperature Sensor -G385-, Right Front Upper Body Vent Temperature Sensor -G386-, Left Footwell Vent Temperature Sensor -G261- and Right Footwell Vent Temperature Sensor -G262-).

-- Using a commercially available thermometer, measure the temperature of the air coming out of the vents in the rear center console (left and right).

Specified values: 

• The temperature at the Right Front Upper Body Vent Temperature Sensor -G386- and Right Footwell Vent Temperature Sensor -G262- increases to above 52 °C (126 °F) (depending on the engine temperature at the time).
• The temperature at the Left Front Upper Body Vent Temperature Sensor -G385- and Left Footwell Vent Temperature Sensor -G261- increases by less than 10 °C (50 °F) in contrast to the measured value of the Evaporator Vent Temperature Sensor -G263-.
• The measured temperature of the air coming out of the vents in the rear center console increases by less than 20 °C (68 °F).

*If the specified values are not reached, check the following: 

• Repeat the heating output at an engine RPM of approximately 1, 500 to 2, 000 (at a low fresh air blower speed on high voltage vehicles). If the heating output is not reached at the engine RPM (fresh air blower speed), the fault is not with the A/C unit but rather inside the coolant circuit (incorporation of the A/C system in the coolant circuit, engine coolant pump delivery, the coolant flowing through the heater core in the A/C unit, etc. Refer to HEATER CORE, REMOVING AND INSTALLING and COOLANT SYSTEM/COOLANT ).
• The activation and function of the Right Temperature Door Motor -V159-, the Left Temperature Door Motor -V159- and the activation of the left and right front temperature doors. Refer to, Right Temperature Door Motor -V159-, REMOVING AND INSTALLING and using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.
• The activation and function of the Rear Temperature Door Motor -V137- and the activation of the left and right rear temperature doors (via the connecting rod). Refer to, Temperature Regulator Door Motor -V68- /Rear Temperature Door Motor -V137-, REMOVING AND INSTALLING and using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.
• Foam seal on heater core for the heater of A/C unit. Refer to HEATER CORE, REMOVING AND INSTALLING .
• The foam seal on the Auxiliary Air Heater Heating Element -Z35- /on the honey comb. Refer to Auxiliary Heater Heating Element -Z35-, REMOVING AND INSTALLING .
• The coolant circuit bleeding. Refer to COOLANT, DRAINING AND FILLING
• The incorporation of the heater core for the heater in the A/C unit into the coolant circuit. Refer to CONNECTION DIAGRAM - COOLANT HOSES
• The separations in the air distribution housing between the left and right side and between rear and front. Refer to OVERVIEW - AIR DISTRIBUTION HOUSING DOORS AND PARTITIONS .
• Coolant regulator (engine coolant may not warm properly if regulator is malfunctioning). Refer to COOLANT PUMP/THERMOSTAT .
• Check the engine coolant pump for proper function (if the coolant pump is defective, it is possible that not enough coolant is flowing through the heater core for the heater in the A/C unit). Refer to COOLANT PUMP/THERMOSTAT .
• For vehicles with a regulated coolant circuit (only installed on certain engines from MY 2011), the activation and function of these components (for example, the regulated coolant pump and the Cylinder Head Coolant Valve -N489-). Refer to COOLANT PUMP/THERMOSTAT .
• The Coolant Recirculation Pump -V50- activation and function (if the coolant pump is faulty, it is possible that not enough coolant is flowing through the heater core for the heater in the A/C unit) using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.

-- Using the knob on the Climatronic Control Module -J255- A/C display and control head, select the "warm" temperature setting on the driver side ("HI" for the driver and front passenger side in the Climatronic Control Module -J255- and MMI display).

-- Read the measured values of the temperature sensor after heat exchanger (Left Front Upper Body Vent Temperature Sensor -G385-, Right Front Upper Body Vent Temperature Sensor -G386-, Left Footwell Vent Temperature Sensor -G261- and Right Footwell Vent Temperature Sensor -G262-).

-- Using a commercially available thermometer, measure the temperature of the air coming out of the vents in the rear center console (left and right).

Specified values: 

• The temperature at the Left Front Upper Body Vent Temperature Sensor -G385- and Left Footwell Vent Temperature Sensor -G261- increases to above 52 °C (126 °F) within five minutes (depending on the engine temperature at the time).
• The temperatures of the temperature sensors displayed in the measure values block (Left Front Upper Body Vent Temperature Sensor -G385-, Right Front Upper Body Vent Temperature Sensor -G386-, Left Footwell Vent Temperature Sensor -G261- and Right Footwell Vent Temperature Sensor -G262-) even out within five minutes (the difference in temperature is less than 5 °C (41 °F) and the temperature is greater than 52 °C (126 °F)).
• The measured temperature coming out of the vents in the left and right side of the rear center console increases but does not reach the displayed temperatures for the temperature sensors (Left Front Upper Body Vent Temperature Sensor -G385-, Right Front Upper Body Vent Temperature Sensor -G386-, Left Footwell Vent Temperature Sensor -G261- and Right Footwell Vent Temperature Sensor -G262-) (temperature has a tendency to be cooler than the setting on the Rear Temperature Selection Potentiometer -G538-). Refer to *If the specified values are not reached, check the following:  above.

If the specified values are not reached, check the following. Refer to *If the specified values are not reached, check the following:  above.

If the specified values are not reached, proceed as follows:

-- Set the Rear Temperature Selection Potentiometer -G538- to "warm" (installed in the rear center console vent).

-- Using a commercially available thermometer, measure the temperature of the air coming out of the vents in the rear center console and the rear footwells (left and right sides) and compare with the displayed measured values for the temperature sensors (Left Front Upper Body Vent Temperature Sensor -G385-, Right Front Upper Body Vent Temperature Sensor -G386-, Left Footwell Vent Temperature Sensor -G261- and Right Footwell Vent Temperature Sensor -G262-).

Specified values: 

• The measured air temperature coming out of the vents in the rear center console and the rear footwell vents (left and right side increases and reaches within 5 minutes a value, which is 10 °C (50 °F) less than the small value measured and displayed by the temperature sensors.
• The deviation between the measured temperature on the left and right side is less than 5 °C (41 °F).

If the specified values are not reached, check the following:

• Check the activation and function of the Rear Temperature Door Motor -V137- and the activation of the left and right rear temperature doors (via the connecting rod). Refer to, Temperature Regulator Door Motor -V68- /Rear Temperature Door Motor -V137-, REMOVING AND INSTALLING and using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.
• Additional tests should the specified values not be reached. Refer to the NOTE: *The activation of the temperature doors for the rear vents (by the Rear Temperature door Motor -V137-)...  above.

If the specified values are not reached, proceed as follows:

-- Using the knob on the Climatronic Control Module -J255- A/C display and control head, select the "cold" temperature setting for the front passenger side ("LO" in the Climatronic Control Module -J255- and MMI display).

-- Compare the measured value of the Evaporator Vent Temperature Sensor -G263- with the measured values for the Right Front Upper Body Vent Temperature Sensor -G386- and the Right Footwell Vent Temperature Sensor -G262- and read the measured values for the Left Front Upper Body Vent Temperature Sensor -G385- and the Left Footwell Vent Temperature Sensor -G261-.

Specified values: 

• The measured and displayed temperatures at the Left Front Upper Body Vent Temperature Sensor -G385- and Left Footwell Vent Temperature Sensor -G261- change slightly and remain greater than 52 °C (126 °F) (depending on the engine temperature at the time).
• The temperature at the Right Front Upper Body Vent Temperature Sensor -G386- and Right Footwell Vent Temperature Sensor -G262- drops and after five minutes at the latest, it reaches a value of maximum 10 °C (50 °F) greater than the values of the Evaporator Vent Temperature Sensor -G263-.

If the specified values are not reached, check the following. Refer to *If the specified values are not reached, check the following:  above. .

If the specified values are reached, the test is complete.