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Direct current motor, air recirculation flap

Direct current motor, air recirculation flap





The air recirculation flap is operated by a DC motor. The flap has only two positions. When the motor has turned the flap to one of the end positions, the current passing through the motor winding is limited by two PTC resistors built into the motor. The ACC control module will also close the output after 10 seconds. PTC means Positive Thermal Coefficient and means that the resistance increases with increased heat (the opposite of NTC).

If the ignition has been turned off for more than 10 minutes, recirculation is selected 30 seconds after starting at the earliest, and only if the outside temperature is above 25˚C and the required mixed-air temperature is the lowest possible (the cabin must be significantly cooled after starting).

Then, recirculation is selected in the following three cases:


• at an outside temperature above 37˚C if the solar intensity exceeds 200 W/m 2 .

• at an outside temperature over 30˚C if the requested mixed air temperature is below 7˚C and vehicle speed is under 5 km/h for a prolonged period of time (A/C system performance drops)

• at outside temperature over 20˚C if coolant temperature is over 118˚C (risk of engine overheating).


Recirculation can be selected manually on the panel. A symbol on the display indicates when the air is recirculated.

With the ignition turned off, fresh-air position is selected after 10 seconds.

Diagnosis

In case of open circuit or short circuit, diagnostic trouble code B2410 is generated, and 21 is shown instead of right temperature at calibration.