Self-Study Programme 208 Air Conditioner in the Motor ... - Volkspage

Air quality sensor G238The sensor operates, in principle, in much thesame way as a lambda probe.The metering element is a mixed oxide sensorwhich uses semiconductor technology (stannicoxide - SnO 2 ).The sensitivity of the air quality sensor isincreased by catalytic additives of platinum andpalladium.The operating temperature of the sensor isapprox. 350 o C. Its power consumption of0.5 watts is very low.Air quality sensor G238+-208_106The evaluation electronics in the sensorThe evaluation electronics integrated in theultrasonic sensor module react to changes insensor conductivity.High sensitivities are achieved.G238Air qualitysensorDigitalsquare-wavesignalThe system is self-learning.The electronics determine the average pollutantconcentration in the ambient air and sendsinformation on the type and quantity of thematerials by means of a digital square-wavesignal to the air conditioner control unit.The control unit now closes the air recirculationflap at peak pollution levels depending on theambient temperature and air pollution level.This ensures that the ventilation system does notremain stuck in air recirculation mode in heavilypolluted areas.Regardless of the electronic evaluation, severalsystems switch to air recirculation mode when thewash/wipe system is operated.ServiceThe air quality sensor is wear-free.The combination filter must be replaced afterservice intervals.AmbienttemperatureAir pollutionlevel> +2 o C LowriseAir recirculationyesmin. 25 sec.> +2 o C Low no+2 o C ... –5 o C HigheryesriseME87< –5 o C HigherriseECON modecompressor offDefrost modeWarm-up phase of sensorapprox. 30 sec.Air conditionercontrol unitPositioning motor forair recirculationmodemax.15 sec.max.15 sec.nono208_10763