BMW 3 series (E90/E91/E92) - Poor air-conditioning system performance | HELLA


3 series (E90/E91/E92)

X5 (E70)

X6 (E71)

Poor air-conditioning system performance

With the above-mentioned vehicles it can happen that, when the weather is extremely damp or humid and when a journey is particularly long, the air-conditioning system will only blow out warm air.

If the air-conditioning system is switched off for 10-15 minutes, it will then function normally again for a certain amount of time.

An incorrectly sealed evaporator temperature sensor is the possible cause.

The evaporator can freeze up because of air infiltrating and the resultant faulty measured values.

To remedy the problem, the temperature sensor, which, for example, in the E90/91/92 is accessible from the front passenger footwell, should be removed and sealed. The cover below the glove compartment is
first to be removed
(Figure 1). The sensor, located on the right side of the evaporator box, can now be seen (Figure 2).

Then proceed as follows:

  • Pull out the sensor connector plug
  • Remove sensor
  • Cut foam strips to size (Figure 3) and stick on

Make sure that the sensor's measuring cell is not covered over (Figure 4)

  • Install the sensor and connect the plug
  • Reposition the cover
  • Carry out functional test

Figure 1


Figure 2



Figure 3



Figure 4


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