Symptom Related Diagnostic Procedures

Eliminating symptoms in body interior - Replacing directional-control valve

General information
Symptoms
Significantly reduced heat output on vehicles with an auxiliary heater after a long journey at a speed of more than 170 km/h (106 mph).

Causes and remedial action
The directional-control heater valve in the auxiliary heater may be defective. If the directional-control valve is defective, there will be insufficient flow through the heat exchanger. Heat output will be reduced significantly. This does not impair engine cooling.

In the event of a complaint, the directional-control valve must be replaced on vehicles manufactured before the date of introduction July 2005.

Tools and materials
955.572.824.02 = VALVE
000.043.203.78 = ANTIFREEZE

Preliminary work
1. Remove heater completely. REFER TO 822019 Removing and installing complete heater - section on "Removing"
2. Remove intake muffler. REFER TO 822119 Removing and installing intake muffler - section on "Removing"

Replacing directional-control valve
1. Remove directional-control valve - section on "Removing"
2. Install directional-control valve - section on "Installing"
Service and Repair

Subsequent work
1. Install intake muffler. REFER TO 822119 Removing and installing intake muffler - section on "Installing"
2. Install complete heater. REFER TO 822019 Removing and installing complete heater - section on "Installing"