Heating Performance, Checking
Heating Performance, checking
Special tools, testers and auxiliary items required
• Vehicle diagnosis, testing and information system (VAS5051B) (or Vehicle Diagnosis and Service System (VAS 5052) ).
• A standard thermometer (for temperature measurements, if necessary a thermometer with 2 measuring probes for simultaneous measurement, for example, for temperature on the right and left)
- Close hood.
- Close doors, windows and rear lid.
- Open all dash panel vents.
- Initiate heating system On Board Diagnostic (OBD) using (VAS5051B) in "Guided Fault Finding".
- Measure the ambient temperature (temperature in workshop)
- Start the engine.
- Place Climatronic control module (J255) temperature knob - A - in "cold" position.
- Adjust Climatronic control module air distribution knob - C - so air flows out of instrument panel vents.
- Place Climatronic control module fresh air blower speed knob - B - in "maximum fresh air blower speed" position.
• The heater works in fresh air mode, the indicator light for the recirculation button - D - does not light up.
• Fresh Air Blower runs at maximum speed.
- In the "read measured values block" function, select (VAS5051B) in "Guided Fault Finding".
- Read the measured values block with the display for the position of the Left Temperature Door Motor (V158). Refer to (VAS5051B) in "Guided Fault Finding".
- Measure temperature of air flowing out of left and right instrument panel vents.
Target values:
• It will display that the Left Temperature Door Motor (V158) is at the "bottom" ("cold").
• The temperature of the air coming out of the left and right instrument panel vents is a maximum of 15 °C greater than the previously measured environmental temperature (the heater temperature increase is less than 16 °C).
• The temperature difference between the air coming out of the left and right instrument panel vents is less than 8 °C.
- Place Climatronic control module (J255) temperature knob - A - in "warm" position.
- Read the measured values block from Left Temperature Door Motor. Refer to (VAS5051B) in "Guided Fault Finding".
- Measure temperature of air flowing out of left and right instrument panel vents.
Target values:
• It will display that the Left Temperature Door Motor is at the "top" ("warm").
• The temperature of the air coming out of the left and right instrument panel vents increases to a value greater than 55 °C (at an engine temperature of approximately 90 °C, depending on the current engine compartment temperature).
• The temperature difference between the air coming out of the left and right instrument panel vents is less than 8 °C.
• The coolant flow rate through the heater core (and therefore the heat output) also depends on the engine speed.
- Place Climatronic control module temperature knob - A - in "cold" position.
- Read the measured values block with the display for the position of the Left Temperature Door Motor (V158). Refer to (VAS5051B) in "Guided Fault Finding".
- Measure temperature of air flowing out of left and right instrument panel vents.
Target values:
• It will display that the Left Temperature Door Motor is at the "bottom" ("cold").
• The temperature of the air coming out of the left and right instrument panel vents decreases within 5 minutes to a value that is a maximum of 15 °C higher than the previously measured environmental temperature.
If the specified values are not reached, check the following:
• If the required heat output is not reached
- Ventilation of coolant circuit.
- Activation and function of Left Temperature Door Motor (V158) using (VAS5051B) in "Guided Fault Finding".
- The foam seal on the heater core. Refer to=> [ Heater Core ] Service and Repair.
- Function of temperature doors in air distribution housing. Refer to=> [ Air Guide In Air Distribution Housing ] Air Guide In Air Distribution Housing.
- Coolant regulator (engine coolant may not warm properly if regulator is malfunctioning).
- The delivery of the engine coolant pump.
• If the air coming out of the vents is too warm when it is set to "Cold"
- Activation and function of Left Temperature Door Motor (V158) using (VAS5051B) in "Guided Fault Finding".
- Function of temperature doors in air distribution housing. Refer to=> [ Heater ] Heater.
- The plenum chamber and seal between engine compartment and plenum chamber.