Functions with Engine Running
-- The coolant fan(s) (Coolant Fan -V7- and Coolant Fan 2 -V177-) run (activation and speed depend on refrigerant circuit pressure and engine temperature).
Depending on the version of the Climatronic Control Module -J255- control head, the coolant fan(s) (Coolant Fan -V7- and Coolant Fan 2 -V177-) are only switched on at a certain refrigerant circuit pressure (currently at a pressure of approximately 9 bar (130 psi)). The activation of the coolant fan(s) is displayed in the "read measured value" function Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
Depending on the Engine Control Module (ECM), the target and the actual speed of the Coolant Fan -V7- and Coolant Fan 2 -V177- can vary from one another. Refer to Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
-- The fresh air blower runs at maximum speed.
The maximum possible fresh air blower speed depends on several conditions (vehicle voltage, etc.)
-- The A/C system goes in recirculating air mode (approximately one minute after starting the engine, the back pressure/fresh air door is closed and the air recirculation door is opened. The fresh air blower extracts the air from passenger compartment below instrument panel/behind the glove compartment).
If one of these requirements is not met, read out the event memory, perform the output diagnostic test mode and read out the relevant measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.