Heated Seats are Useless
#31
Originally Posted by Hyde
those that thinks it works fine definatly never used one on a BMW......
the heated seat hardly even feel warm.
the heated seat hardly even feel warm.
It wasn't like it was comfortable driving for a long time on the highest setting anyway.
#34
#36
Does anyone know if the heaters are thermally triggered? I know some cars have that where if its 80 degrees outside they are very low but if its -30 degrees they are on full blast? Mine are ok depedning on the outside temp.
Also I totally agree about Saab / Volvo they have the BEST seat heaters ever - I disconnected the thermal switch on my driver seat in the winter - wow it was like sitting on top of an oven
Also I totally agree about Saab / Volvo they have the BEST seat heaters ever - I disconnected the thermal switch on my driver seat in the winter - wow it was like sitting on top of an oven
#37
My G35 heated seats work fine, as did my previous I30 seats. High gets hot in about 3-5 minutes and after a bit I have to turn them to low. My Saab (late 70s) had heated seats that didn't work, so I figured it was just a Saab problem. After about three years they worked better when I connected the wire under the seat that had never been attached! You might look for that, or have the dealer do it. Unless you are wearing VERY thick clothes, you should easily feel the high setting. I've never noticied them turning themselves off.
My earlier Audi (many problems) had a similar top temperature and six total settings. I find having only high and low settings just fine.
My earlier Audi (many problems) had a similar top temperature and six total settings. I find having only high and low settings just fine.
#39
Join Date: Mar 2003
Location: Alexandria, VA (metro DC)
Posts: 663
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Heated Seat Control Logic
For all you engineering geeks, here's a little info on how the heated seats are controlled. All of this was based on my 2004 sedan FSM, and it may have changed for later models. In some ways, the heated operation is more complicated than has been observed, and in some ways it's simpler:
1. First, there is no occupancy sensor. The operation of both seats is without regard to whether or not someone is sitting in the seats.
2. Each seat has a total of four heater elements. One is in the seat back, and three are in the seat cushion. The seat cushion elements consist of a single "main heater", and two "sub heaters".
3. In the LOW setting, 12V power is applied to all four heater elements in series. In this mode, the seats are not under thermostatic control. My assumption is that when the elements are powered in series (nominally 3V per element), this significantly limits how hot they could get, making thermostatic control unnecessary.
4. In the HIGH setting, the above four-elements-in-series circuit remains on, but two of the three seat cushion elements (the main and one sub heater) are provided another 12V source, again in series (but now nominally 6V per element). This second circuit is under thermostatic control. In fact, there are two thermistors in series, which I would presume to be a safety configuration. (If one thermistor fails in the closed position, the other can still override and shutoff).
5. In this second circuit, the thermistors settings are as follows:
--open the circuit in a temperature range of 95-133F
--close the circuit in the range of 77-95F
These ranges are surprisingly broad AND they are exactly adjacent! This may be the reason for the variable performance that many have observed. And yes, the control on this circuit would allow it to cycle on and off, especially if yours are tuned around 95F!
Thought this might be interesting...
1. First, there is no occupancy sensor. The operation of both seats is without regard to whether or not someone is sitting in the seats.
2. Each seat has a total of four heater elements. One is in the seat back, and three are in the seat cushion. The seat cushion elements consist of a single "main heater", and two "sub heaters".
3. In the LOW setting, 12V power is applied to all four heater elements in series. In this mode, the seats are not under thermostatic control. My assumption is that when the elements are powered in series (nominally 3V per element), this significantly limits how hot they could get, making thermostatic control unnecessary.
4. In the HIGH setting, the above four-elements-in-series circuit remains on, but two of the three seat cushion elements (the main and one sub heater) are provided another 12V source, again in series (but now nominally 6V per element). This second circuit is under thermostatic control. In fact, there are two thermistors in series, which I would presume to be a safety configuration. (If one thermistor fails in the closed position, the other can still override and shutoff).
5. In this second circuit, the thermistors settings are as follows:
--open the circuit in a temperature range of 95-133F
--close the circuit in the range of 77-95F
These ranges are surprisingly broad AND they are exactly adjacent! This may be the reason for the variable performance that many have observed. And yes, the control on this circuit would allow it to cycle on and off, especially if yours are tuned around 95F!
Thought this might be interesting...