Heating Performance, Checking

Heating Performance, Checking

The heat output test requirements are met. Refer to => [ Heat Output Test Requirements ] Heat Output Test Requirements.

- Close hood.

- Close doors, windows and rear lid.

- Open all dash panel vents.

- Perform OBD on the A/C system. Refer to Vehicle diagnosis, testing and information system (VAS5051B) under "Guided Fault Finding".

- Start engine and let it run a few minutes with maximum cooling output (A/C compressor is switched on, indicator light on AC button lights up).

- In "read measured values block" read the display for the A/C compressor regulator valve (N280) actuation and refrigerant circuit pressure. Refer to Vehicle diagnosis, testing and information system (VAS5051B) under "Guided Fault Finding" (the A/C compressor will be actuated and the refrigerant circuit pressure is OK. Refer to => [ Cooling Output, Checking ] Cooling Output, Checking.

- Turn the Climatronic control module (J255) temperature rotary switch to "cold".

- Adjust air output direction via the air distribution rotary switch on the Climatronic control module to "footwell".

- Read the measured values from the left footwell vent temperature sensor (G261) , from the right footwell vent temperature sensor (G262) and from the evaporator vent temperature sensor (G263). Refer to Vehicle diagnosis, testing and information system (VAS5051B) under "Guided Fault Finding".

- Check and compare the displayed values from the left footwell vent temperature sensor, from the right footwell vent temperature sensor and from the evaporator vent temperature sensor with each other.

• Temperature maximum 12 °C (depending on ambient temperature), deviation between measured values less than 3 °C.

- Adjust air output direction via the air distribution rotary switch on the Climatronic control module to "Instrument panel vents".

- Check and compare the measured values from the left front upper body outlet temperature sensor (G385) and from the evaporator vent temperature sensor.

• Temperature maximum 12 °C (depending on ambient temperature), deviation between measured values less than 3 °C.

- Place Climatronic control module temperature rotary switch in "Warm" stop.

- Place fresh air blower rotary switch in "maximum speed" stop.

- Adjust air outlet direction (using air distribution rotary switch on Climatronic control module) so an approximately equal portion of air comes out of "instrument panel vents" and "footwell vents".

• The air distribution rotary switch can also be adjusted so air only comes out of "instrument panel vents" or "footwell vents". In that case, only the measured value from the temperature sensor installed in the selected vent may be used (if necessary, adjust air output direction so it alternates between "instrument panel vents" and "footwell vents").

- Check and compare the displayed values from the left front upper body outlet temperature sensor, from the left footwell vent temperature sensor and from the right footwell vent temperature sensor with each other.

Target values:

• The temperature goes above 55 °C (depending on the engine temperature) in the display fields with the measured values form the left front upper body outlet temperature sensor, from the left footwell vent temperature sensor and from the right footwell vent temperature sensor.

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

- Ventilation of coolant circuit.

- The integration of the heater core in the coolant circuit.

- Activation and function of Left Temperature Door Motor (V158) and of Right Temperature Door Motor (V159)=> [ Temperature Increase Downstream from Evaporator, Determining Malfunction ] Temperature Increase Downstream from Evaporator, Determining Malfunction, => [ Heating Performance Of A/C System, Checking ] Heating Performance Of A/C System, Checking and Vehicle diagnosis, testing and information system (VAS5051B) under "Guided Fault Finding".

- Foam seal on heater core for heater of A/C unit. Refer to=> [ Heater Core ] Service and Repair.

- Function of temperature doors in air distribution housing, refer to => [ Air Routing and Distribution in Passenger Compartment ] Air Routing and Distribution in Passenger Compartment.

- Coolant regulator (engine coolant may not warm properly if regulator is malfunctioning).