I bet this has been covered before, but I can't find it. Thanks.<p>David

Yes during the past week, I've noticed that the snowflake light seems to be inconsistent. Here in Toronto, Friday was about -15 degrees Celcius (but dry) and the snowflake light was off, but yesterday, it was almost the same temperature but was snowing, and the snowflake light was on.<p>Maybe it measures humidity with the temperature as well..... can someone confirm ??<p>Gordon<br>98.5 1.8TQMS

Mine turns off at 35 degrees (f) The owners manual states this is normal. Would be curious regarding the reason behind this. The AC acts as a dehumidifer and is required to defrost the car...

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Below the freezing point, a vapor compression refrigeration system is useless in lowering the relative humidity when the evaporator is the first heat exchanger in the system. The evaporator would have to remove the humidity as a solid, a phase which dosen't flow well. <p>Having the evaporator covered in ice isn't good for the life of a system as the ice acts as an insulator, possibly allowing liquid refrigerant to enter the low side of the compressor. All systems require superheated vapor at this point in the system. Liquid R-134a would deprive the compressor of lubricant, grinding it to a lump od metal fragments.<p>This design causes momentary fogging of the interior window surfaces during transitory periods. If you are driving in weather where the temperature does drop within the compressor shut-off range, hit the defrost button IMMEDIATELY, especially if there is a high outside relative humidity. (This happened to me over the Christmas exodus, defrost worked fine even after heavy fogging) Visibility is paramount to safety, especially in marginal conditions. (Thanks to those drivers ignoring the ice warnings on I-10 the evening of Dec 23! :-( And those w/ fogged windows!!!)<p>Keith

Mine stays on from about 40F to (at least) -5F.<br>

Cars and ice skates. It's slippery because the force of the car on the ice melts the top of the ice, causing the car to plane. It takes more force as it gets colder, to the point there is no longer enough force to melt any, and it is no longer as slick.