At Dial Position 22 Degrees, System Does Not Attain 24 Degrees

COMPLAINT:
At selector dial position 22 °C and outside temperatures below 0 °C the system does not attain a temperature of approx. 24 °C at head room level.

Cause/Remedy:
a) In-car sensor, temperature sensor for heat exchanger or temperature dial are not attaining specified resistance value.

Test in-car sensor, temperature sensor for heat exchanger or temperature dial and renew, if required, or test their supply lines for ground connection and repair.

b) Heat exchanger contaminated or damaged.

Checkup: Push "DEF" pushbutton switch. Plug thermometer into defroster nozzle left and right. Start engine and run up to operating temperature (min. 80 °C). Keep engine running at approx. 2000/rpm for 5 minutes. Then read thermometer, readout should be approx. 55 °C. Flush heat exchanger and renew. if required.






c) Recirculating pump (30) not running.
Check recirculating pump and renew, if required. or check its supply line and recondition.






d) Electronic switching unit for temperature control (9) damaged.
Renew electronic switching unit.