Determining Malfunction Of Temperature Increase Downstream From Evaporator

WARNING: This page is about a different variant/trim than selected.

The temperature increase in the A/C unit is too great. Refer to COOLING OUTPUT, CHECKING , COOLING OUTPUT, CHECKING and COOLING OUTPUT, CHECKING, VEHICLES WITH AUTOMATIC CLIMATE CONTROL SYSTEM (WITH HIGH VOLTAGE SYSTEM) .

NOTE:

This Service Information only outlines the checking procedure. Perform the detailed test for this heater function as described in the Guided Fault Finding. Refer to Vehicle Diagnostic Tester in the"Guided Fault Finding" function.

If a target value is not reached due to a temperature increase downstream from the evaporator, this can be caused by various things:

-- Determine the cause. Use the :Vehicle Diagnostic Tester in the"Guided Fault Finding" function.

Possible causes for the deviation of the target value:

Due to a fault in the activation, the temperature doors do not reach the end stops correctly in the A/C unit.
One or several measured values of the temperature sensors are faulty.
Warmed up air flows by the temperature doors set in the "cold" position.

NOTE:

This fault can be determined as follows: Clamp off both coolant hoses from the engine to the A/C unit heater core using, for example, the :3093 and then repeat the cooling output test. If the measured values are then OK, this indicates a fault near the temperature doors.