Heated Seat Max & Min Temperature Operation

[trebor]

Many of you will know that i am not satisfied with my heated seat operation as they take a while to get warm and then switch off after a short while and do not compare favourably to some other heated seats in other cars.

It is a problem that keeps nagging away at me so i have done a bit more research and found out that each heater element is controlled by a thermostatic sensor inside the seat which maintains the heater element at a temperature of up to a maximum of 40°C (104°F). If the seat temperature is
above 20°C (68°F) and the heated switch is selected on, the seat heaters will not operate until the temperature drops to below 20°C (68°F).

This raises 2 issues:

1) The guidance says that the seat has a thermostat inside the seat which maintains a temperature of 40c so why does it switch off, i am not 100% sure on this but it is thought there is a timer in the dash switch causing it to switch off after a set time ( 15 minutes in my case )

2) The seat will not operate until the seat is below 20c, this explains why it switches on from cold but will not switch back on after it has gone off, presumably because the seat is over 20c and stays above whilst your backside is still on the seat.

So what is my theory to improve the operation,

1) Well first of all i could hover over the seat whilst driving when it switches off to allow the seat to drop below 20c and switch it back on( not recommended )

2) Or i could by pass the timer which should allow the thermostat inside the seat to maintain 40c as long as i want it to ( favourite idea )

3) Replace the thermostat inside the seat with one that has different tolerances but i woudnt know where to get one from and it would still switch off after the alloted time ( i bought an aftermarket one from Maplins to try and the upper tolerance on that is 50c it works fine and gets really warm so much so that you need to switch it off, or put on the low setting, yes it has 2 settings and all for £9.99, only drawback is that it doesnt come in Sandstone ! )

I may experiment by connecting one of the seats to a different switch to see if that solves the timer problem.

Anybody any further comments/opinions ?

[stevemac]

This is worth pursuing Rob, as mine does the same. Really annoying.

[2Diesels]

Option 1 in my opinion Rob as it's by far the cheapest

I'll check out the temperature ranges for a swedish seat (see how I avoided saying Volvo there) & let you know but it certainly sounds like they're on a timer to me & bypassing would be the way I would go

Regards Col

[JohnDotCom]

I'll check out the temperature ranges for a swedish seat (see how I avoided saying Volvo there)

Thats it I'm adding Volvo to the swear filter,
or
Banning 2Diesels.

[2Diesels]

But I didn't say Volvo I cleverly avoided it

[Matt1960]

trebor,
Yes I have thought about this too, as my seat is the same as yours.
I cannot think why they would put a timer in the switch as well as a thermostatic control, so my guess is that it might be a relay that operates once the seat thermostat cuts the element off. This would mean the element only comes on when the ignition is switched off and on again.
However it might be a timer?

I have thought about another bi-metalic spring thermostat in the seat and they are readily available at 50c and they look like they switch off at 50c and cut back in at 35c which looks perfect.

http://www.rapidonline.com/productin...moduleno=35569
But it means taking the seat apart to resolder this in. I dont know how difficult this is?

I have also been thinking of another solution which is slightly insulating the existing thermostat, by putting something like a small piece of corrugated cardboard or such like over the thermostat. I wondered if you might even be able to reach the thermostat by getting your hand under the seat cover without any dismantling at all from the rear and below?
Anybody know?
Or burying the existing thermostat more into the foam base somehow?

I am not sure I have the time to experiment at the moment.

Anyway just some thoughts, thinking out of the box a bit.

Matt

[raykay]

According to the manual there is no mention of a timer, but there are electronics in the switch, the sensor does not maintain 40 degrees, it switches off.

As I understand it, the feed is from the fuse, through its own contacts in the ignition switch to each dash switch and heater, (the switching is in the earth, not 12v) when the switch is pressed, it creates an earth path for the heater and switch and the heater is on.

When it reaches 40 degrees, the earth path is broken the heater goes off, as does the switch, which will not switch on again until the feed has been switched off and then on again by the ignition switch.

[Matt1960]

Ray,
Thank you for that. Unfortunately I have only little understanding of electrics/electronics, so does that mean that if a new thermoswitch were fitted that would cycle between 35c and 50c, the seats would still not stay permenantly on because of the circuitry?
Matt

[stocktake]

I can follow that.

So, if we find a seperate live to the switches the seat will at least come on and go off between 20 deg and 40 deg. Then if we change the stat to a 35 - 50. problem solved?

Or is the drop out in the switch itself?

[trebor]

iam just about following this and dont mind experimenting on my car but will need a little advice along the way