Checking the heating element of the additional air heater

Periphery of heater element for auxiliary air heater -Z35- (load signal for alternator terminal DF, relay for low heating output -J359-, relay for high heating output -J360-, intake air temperature sender -G72-, coolant temperature sender -G62-) can be checked by self-diagnosis of the engine control unit.

Check condition

• The intake air temperature is below 19°C.
• The coolant temperature is below 80°C.
• The temperature in the cabin is about 20°C
• Battery voltage exceeds 11 V.
• Generator load does not exceed 50% (terminal DF)
• Engine speed exceeds 450 rpm
• Internal temperature regulator in the maximum heating position

Check procedure

Remove left footwell air duct. Remove trim for center console in footwell on left side. Measure earth current arrow- using tester -VAS 5051B- and 100 A current clamp -VAS 5051 V/7-.

• Low heat = 30 amps
• Average heating = 00 amps
• Strong heat = 80 amps

Removal and installation

Remove the footwell trim on the driver's side. Remove left footwell air duct. Loosen screws -A- and remove cover -B-.

Note: The operating lever -C- of the temperature control damper can be positioned so that access to the bolt -A- is blocked. In this case, change the position of the temperature control flap using the temperature control knob, and for vehicles with air conditioning using the display and control panel, for example. In the direction of increasing temperature ("Hi").

Disconnect the battery. Loosen nut -1- (9±1 Nm). Unclip retainer for connector strip -arrow-.

WARNING: Beware of burns. The auxiliary air heater element -Z35- may be hot. Wait until heating element -Z35- has cooled down before removing.

Remove bolt -2- (1.4 Nm) and remove heater element -Z35- from fan housing.

Installation is carried out in the reverse order.