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

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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" operating mode (indicator lamp in the AUTO button lights up).
Temperature preset "cold" ("LO" 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 MMI display, setting "10" or greater).
Set the airflow direction using the knob on the A/C display and control head to "footwell vents" and "instrument panel vents" (displayed in the MMI display).

NOTE:

The indicator lamp in the AUTO button goes out when the vent direction for the air or fresh air blower speed is manually changed.

The maximum possible fresh air blower speed depends on several conditions (coolant temperature, vehicle voltage, etc.)

-- 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 displayed measured value for the Evaporator Vent Temperature Sensor -G263- with the measured values of the Center Vent Temperature Sensor -G191- and the Footwell Vent Temperature Sensor -G192-).

Specified values:

The measured values for the Center Vent Temperature Sensor -G191- and Footwell Vent Temperature Sensor -G192- may not be greater than maximum 5 °C (41 °F) after five minutes than the Evaporator Vent Temperature Sensor -G263- measured value.

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 temperature coming out of the instrument panel vents (left, right and center) and out of the front and rear footwells and compare the measured values with displayed measured values from the Center Vent Temperature Sensor -G191- and the Footwell Vent Temperature Sensor -G192-.

Specified values:

The measured values with the thermometer may be maximum 5 °C (41 °F) lower or higher than the measured values from the Center Vent Temperature Sensor -G191- and the Footwell Vent Temperature Sensor -G192-.

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 ("Hi" in the MMI display).

Specified values:

The measured values from the Center Vent Temperature Sensor -G191- and the Footwell Vent Temperature Sensor -G192- in the display fields are greater than 52 °C (126 °F) (depending on the engine temperature at the time).
The measured values (temperature of the air coming out of the vents), after 5 minutes, may be maximum 5 °C (41 °F) greater or smaller than the measured values from the Center Vent Temperature Sensor -G191- and the Footwell Vent Temperature Sensor -G192-.

NOTE:

Depending on the engine, for example, on the 8-Cylinder engine, it may be necessary to increase the engine RPM from 1, 200 to 1, 500 to reach the required temperature. The heating output of the engine or coolant flowing through the heater core may not be sufficient when the engine is running in idle to bring the necessary warming energy into the heater core (for example, on an 8-Cylinder engine with an idle RPM of approximately 650).

At the "warm" temperature setting, the specified outflow temperature at the evaporator is controlled to approximately 10 °C (50 °F) by the Climatronic Control Module -J255- A/C display and control head.

On high voltage vehicles, reduce the Fresh Air Blower -V2- speed if necessary. The Coolant Recirculation Pump -V50- delivery is not always enough to supply the requested heat output when the engine is not running and the fresh air blower is set to the highest setting.

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 for 2.0L, COOLANT SYSTEM/COOLANT for 3.0L, or COOLANT SYSTEM/COOLANT for 3.2L).
The coolant circuit bleeding. Refer to COOLANT, DRAINING AND FILLING for 2.0L, COOLANT, DRAINING AND FILLING for 3.0L, or COOLANT, DRAINING AND FILLING for 3.2L
The incorporation of the heater core for the heater in the A/C unit into the coolant circuit. Refer to CONNECTION DIAGRAM - COOLANT HOSES for for 2.0L, CONNECTION DIAGRAM - COOLANT HOSES for 3.0L, or CONNECTION DIAGRAM - COOLANT HOSES for 3.2L
The activation and function of the Temperature Regulator Door Motor -V68- and the actuation of the temperature doors (via the connecting rod). Refer to, 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 .
Coolant thermostat (engine coolant may not warm properly if the thermostat is malfunctioning). Refer to COOLANT PUMP/THERMOSTAT for 2.0L, COOLANT PUMP/THERMOSTAT for 3.0L, or COOLANT PUMP/THERMOSTAT for 3.2L .
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 2.0L, COOLANT PUMP/THERMOSTAT for 3.0L, or COOLANT PUMP/THERMOSTAT for 3.2L .
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 for 2.0L, COOLANT PUMP/THERMOSTAT for 3.0L, or COOLANT PUMP/THERMOSTAT for 3.2L .
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.

NOTE:

The Coolant Recirculation Pump -V50- is not installed on all vehicles (depending on the version, engine and when the vehicle was manufactured). The Recirculation Pump -V55- works as the Coolant Recirculation Pump -V50- on vehicles with an "parking heater". The Auxiliary Heater Control Module -J364- activates the Recirculation Pump -V55- upon request of the Climatronic Control Module -J255- A/C display and control head when the engine RPM is low to support the engine coolant pump, depending on the vehicle version and the adaptation of the Auxiliary Heater Control Module -J364-, using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

The Coolant Pump -V50- maintains the coolant flow through the heater core for the heater in the A/C unit when the engine is not running on vehicles with a Start/Stop System and on high voltage vehicles.