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, VEHICLES WITH MANUAL CLIMATE CONTROL SYSTEM or COOLING OUTPUT, CHECKING, VEHICLES WITH AUTOMATIC CLIMATE CONTROL SYSTEM .

NOTE:

This Service Information only outlines the testing procedure. Perform the detailed test for this heating function as described in Guided Fault Finding. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function (for the Climatronic Control Module -J255-).

If a specified value is not reached due to a temperature increase downstream from the evaporator, this may have various causes:

-- Determine the cause using the Vehicle Diagnostic Tester in the"Guided Fault Finding" function (for the Climatronic Control Module -J255-).

Possible causes for the deviation from specified value:

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

NOTE:

This fault can be determined as follows: Clamp off both coolant hoses from the engine to the heater and A/C unit heater core using, for example, the Hose Clamps - Up To 40mm :3093 and then repeat the cooling output test. If the measured values are then OK, this indicates a malfunction involving the temperature control doors.