EniGmA1987 wrote: The M uses what is called a Thermo-Electric Cooler, TEC. Basically one side is hot and one side is cold. The fan takes air off of the top plate and blows it through the ducting in the seat, by changing which side the hot plate is on (top or bottom) you control if the fan takes hot air or cold air from the TEC to blow into the seat. Thw way the hot plate is controlled is by the voltage going to the TEC. I believe the TEC units in the M are little 35w units. The max setting for each temperature provides the full voltage to the TEC (or maybe over-volts it a bit?) and the lowest setting under-volts the TEC so it doesnt give off as much hot/coldness. the seat heating/cooling works independantly of the main AC system, you can turn the seats on max hot and the AC down to 50 degrees if you wanted to.
Perhaps if the fan is not working it shuts the system off to prevent damage since air is not being taken away from the TEC. Since the system goes into fault mode and shuts down, it wont work until the car is restarted which has cleared the memory.
Great stuff as always
I'm going to take a shot in the dark but here is what I think.
Since the M uses a really neat (read;complex
) seat air conditioning system airflow is critical to the operation. As the seats settle over time the small vent passages start to collapse and restrict airflow through bottom of the seat. The restriction to motion of the air causes the seat TEC thermal sensor to reach its' cutoff temperature much faster than previously.
The bad side is that is not typically something the company will pay for. Even with warranty this is typically* (*all cases are different) considered wear and tear. It does not require a driver of size either, one of my regulars is a Fed who can't be more than 180 and has the same problem and as far as I know has had no luck getting his replaced. Although the cushion is about $600 and I would recommend a top quality upholstery shop.
Here a few random facts about the system just in case you all are curious;
The climate controlled seat system is controlled by climate controlled seat control unit.
Heating and cooling are possible for a thermal electric device (heat conversion machine).
-The climate controlled seat system is downed when the temperature sensor set as the seat cushion and
the seat back's thermal electric device machine detects 20 °C (68 °F)or more of mutual differences of temperature.
-In this case, by turning off ignition switch, system down is canceled and it can be reused by turning on
ignition switch again.
-The climate controlled seat blower keep low speed for approximately 60 seconds after turning the climate
controlled seat switch
Unfortunately the sensor is not serviceable and other than a resistance verification there is nothing you can really do to prove this system works. My advise you be crank it up on cold and put the side of you cheek and see if you feel the lightest breeze.....honestly that the amount of air is so light that it is really hard to notice. Unbolt the seat and check out what things look like in there.