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Essential equipment Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Mon, 21 Oct 2002 12:07:46
In Reply to: seat heaters, MS, Sun, 20 Oct 2002 12:38:16 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Your prior car also had heated seats. Seat heaters have been standard in Saabs since around '73.
There are two forms of heated seats. The common one for the 900 is the 'automatic' heated seat. When the ignition is on, 12 volts flows to the seat. There is a thermoswitch in series with the seat heater. When the temperature of the seat falls below 50F, the switch closes, and the heating element heats up. When the seat temperature reaches 80F, the switch opens. No user control. This is true for the driver's side. For the passenger, there is a spring-loaded switch under the seat that only enables the seat heater if someone is sitting in the seat. The assumption is that there is always a driver, so there is no occupant switch.
The other method has a controller in the instrument panel. This was in the later ( post '88)900 and most 9000's. You can tell it by the 4 position rotary 'wheel' switch. It uses a different method. This has been called a 'rheostat', but it isn't. It's an actual controller, that measures the seat temperature with a temperature sensor, and supplies 12 volts through a relay to heat the seat up.
If your seat isn't heating, the most probably reason is that the heating element is broken. This commonly happens at the front outside of the bottom cushion, which gets most abuse when getting in and out of the car. The solution is to peel back the seat cover and re-solder the break in the wire. Very simple.
When working normally, the seat just gets warm on cold mornings. With the automatic heaters in your 900, the seats don't get very hot. When working normally, you may not even notice. But the seat and back will get warm. The adjustable heaters allow you to set the heat much higher and be more noticeable.
As to fire, the seat heater element DOES NOT EVER get hot enough to cause a fire. You can supply 12 volts to the heating element all the time - it will get warm, but it WON'T cause the seat cushion material to burn.
When the heating element wire breaks, there can be some sparking at the break. I usually see a slight burn mark in the seat foam where the break occurs - it makes it easier to find. The wires usually move apart and there is no more sparking.
I guess it is possible that with enough sparking and under just the right conditions, the seat cushion could catch fire. But except for the one example stated here, I've NEVER heard of it.
Given the fact that most every auto manufacturer installs heated seats these days, the number of seat fires has to be between incredibly rare and never. Audi puts in a seat heater that gets hot enough to render lard. If Audi, who was almost driven out of business by the 'Unintentional Accleration' lawsuits installs seat heaters, you know they're safe.
I love the seat heaters. They help my aching back, and keep me comfortable. I consider them safety equipment. If you're not comfortable, you're not able to pay full attention to your driving, and are less safe.
posted by 192.249....
, Mon, 21 Oct 2002 12:07:46 <-- Viewing This Message, Sun, 20 Oct 2002 19:56:08
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