Auxiliary Air Heater Heating Element (Z35) With Control Module (J604)
Auxiliary Air Heater Heating Element (Z35) with Control Module (J604)
• An electric auxiliary air heater is currently installed in vehicles with diesel engine. In this system, the air is supplied with heat energy after it has left the heater core of the heater / A/C unit, in the event a request from the Climatronic Control Module (J255) / or from the A/C Control Module (J301) is present. The electric auxiliary air heater is controlled by the auxiliary air heater control module (J604) or by the engine control module (on the 3-stage version by the Low Heat Output Relay (J359) and the High Heat Output Relay (J360) ). Check using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" (Guided Fault Finding for each engine control module).
• The electric auxiliary air heater is available in different versions. On vehicles equipped with a diesel engine built through November 2006 (running change) the control of the auxiliary air heater heating element is via the auxiliary air heater control module. Check using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding". On vehicles with Diesel engine manufactured later than November 2006 (running change in production), a 3-stage Auxiliary Air Heater Heating Element is installed, which is actuated via a relay by the respective Engine Control Module (ECM).
• At this time, an auxiliary air heater heating element is also installed in vehicles with Diesel engine and parking heater as optional equipment. At a later point in time (not yet finalized), the auxiliary air heater heating element will be discontinued, then the parking heater undertakes the function of the auxiliary heater.
• Functional testing of the electric auxiliary air heater activation on a vehicle with a auxiliary air heater control module (J604) is described in Guided Fault Finding of the A/C system using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding".
• Measuring value block of auxiliary air heater control module indicates that auxiliary heater is switched on or why no activation is occurring despite a request. Check using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding".
• Functional testing of the electric auxiliary air heater activation on a vehicle with a 3-stage auxiliary air heater heating element is described in Guided Fault Finding of the respective ECM. Use Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding".
• At this time, no auxiliary heater is installed in vehicles with gasoline engine.
• Only air distribution housings with an opening for an auxiliary heating element are available as replacement parts. In vehicles without auxiliary air heater heating element , the opening is sealed by cover for heater core (different versions). Refer to Electronic Parts Catalog (ETKA).
Removing
- Remove driver side storage compartment.
- Remove center console.
- Remove left footwell vent - A - (driver side).
- Remove the bracket - B -.
- Remove 4 bolts - A - and remove cover - B -.
• There are different version of the cover - B - (vehicles with or without an electric auxiliary heater). Refer to the Electronic Parts Catalog.
• If lever to left temperature door is located unfavorably so that upper bolt - A - is not accessible, switch ignition on and select a different temperature setting on Climatronic Control Module (J255) for the left side (e.g. "Hi" setting).
Further procedures for vehicles with Auxiliary Air Heater Control Module (J604)
- Switch off ignition.
- Disconnect voltage supply to auxiliary air heater heating element by pulling out corresponding fuse (100 A at this time), component location of fuse can be found in corresponding wiring diagram.
- Disconnect harness connector - A - from heating element - D -.
- Check between connections - C - (positive) and - B - (negative) e.g. using a voltage tester, there must no longer be any voltage present (danger of short circuit).
- Mark both wire connections to Auxiliary Air Heater Heating Element (Z35) (risk of interchange, only on vehicles with Auxiliary Air Heater Control Module (J604) ).
• If connection assignments were interchanged, Auxiliary Air Heater Control Module can no longer regulate the current and Auxiliary Air Heater Heating Element is continuously supplied with current (unregulated at maximum heating performance).
- Disconnect both wire connections - B - and - C - to Auxiliary Air Heater Heating Element (tightening specification of hex nuts 6 Nm) and insulate connection points (danger of short circuit).
- Pull Auxiliary Air Heater Heating Element - A - (with Auxiliary Air Heater Control Module - B -, cannot be tested or replaced individually) from A/C unit (from heater unit).
Further procedures for 3-stage Auxiliary Air Heater Heating Element (Z35) (without Auxiliary Air Heater Control Module (J604) )
- Switch off ignition.
- Remove the hex nuts - A - (tightening specification: 6 Nm).
- Disconnect connector - B - from auxiliary air heater heating element- C -.
- Pull auxiliary air heater heating element - B - out of heating & A/C unit (out of heater).
Installing
Now install all removed components in reversed order.
• Hex nuts at both wire connections - B - and - C - to auxiliary air heater heating element are tightened to 6 Nm (electronics of auxiliary air heater heating element are damaged if torque is too great).
• The nut - A - on the connector - B - and the ground for the auxiliary air heater heating element - C - is tightened to 6 Nm. Tightening too much will damage the auxiliary air heater heating element.
- After installing, check the control and the function of the auxiliary air heater heating element using Vehicle diagnosis, testing and information system (VAS5051B) under "Guided Fault Finding" (on vehicles equipped with A/C) and => [ Auxiliary Air Heater Heating Element (Z35) Activation, Testing (Without A/C) ] Auxiliary Air Heater Heating Element (Z35) Activation, Testing (Without A/C) on vehicles without A/C.