Heated seats

ozturbo · Post by **ozturbo** » Fri Jun 01, 2007 2:50 am

Does anyone know if it is possible to modify the seat heater switches so that you can switch them on whenever you want like you can in most cars? I believe they are connected to a sensor so that they only come on when the outside temperature is below a certain amount. The trouble is, here in South Australia it doesn't get that cold very often but is still cold enough to use the heaters. Also I am not sure if the heaters are working properly so if there are any common problems to look for I would like to know what they are.

guitarcarfanatic · Post by **guitarcarfanatic** » Fri Jun 01, 2007 7:18 am

Unfortunately the temp sensor is located in the seat and is a bit of a pig to get to \(having to dismantle all the seat and pell all the covering off.I believe it is on the base of the seatand is held to the element by some glue like stuff. If you can get the seat covers off ok, and could get to the thermistor, if you removed it and put a direct wire across, it would no longer be temp dependant. You would just have to be quick on the switch as I have heard stories of 400 series cars seats catching fire when those thermistors failed in the past.

Search on here for seat repair and I think one of teh repair threads shows a picture of the thermistor sat in the base.

ozturbo · Post by **ozturbo** » Fri Jun 01, 2007 9:00 am

What does the temp sensor actually do though? This doesn't quite make sense because why would the seat catch fire if you removed it? I thought it only controlled the switching on. I used to have a SAAB and you just had 3 different temp settings to choose from but they didn't switch themselves off. You just switched the heater off when you had had enough.

guitarcarfanatic · Post by **guitarcarfanatic** » Fri Jun 01, 2007 9:13 am

The temp sensor turns the seat on when it gets below 14C and then when the temp reaches 36C it turns it off. If the temp sensor doesn't turn the element, I can only assume it gets so hot it starts to burn the fabric.

ozturbo · Post by **ozturbo** » Fri Jun 01, 2007 10:45 am

Thanks for your input.
I just looked up my owners manual and it says:

"Switch depressed: the seat heating comes on automatically at temperatures below 14C and cuts out at approximately 27C"

That sounds like it simply switches it on and off according to the temperature in the cabin or outside, it doesn't say which. I wouldn't think the element would be designed in a way that allows it to heat the seat to burning point. After all an electric radiator doesn't keep getting hotter indefinitely. I still think there must be a way to bypass the sensor. As I said, the SAAB ones could be turned on and off whenever you wanted. They were powered via the ignition switch so they wouldn't stay on when you left the car.

guitarcarfanatic · Post by **guitarcarfanatic** » Fri Jun 01, 2007 12:58 pm

The temperature is measured by the little switch that turns it on and off. That will need to be remove to bypass the on off according to temperature thing. With regard to seats burning, It has come up a few times on here.

Here is a link to a tread where it was mentioned http://volvo480.dragons.org.uk/forum/vi ... ht=burn%2A

ozturbo · Post by **ozturbo** » Fri Jun 01, 2007 1:32 pm

Thanks for that link. I think it might have answered my question. Here is what autobahnstormer said:

"Just repaired mine for about the fifth time, and I also noticed (or didn't) that the seats were getting warm. I flayed the seat, took the thermostats out, and now have a nice toasty warm bum when I drive to work. If it gets too hot? Switch it off!! "