It's feasible that using the air-con in addition to the climatic seat, may increase its effect or speed up the seat cooling as the cooling cells in the seat would be cooling a lower ambient temperature. It seems that as above, they are designed to work independently of each other. A couple of days ago, I used the maximum cooling setting on my seat but switched off the air con as I preferred the drivers window open. My seat cooling was pretty effective at the base and lower back.
I suppose even the movement of air can feel like it has a cooling effect, as in a desktop fan. It seems the climatic seats are more advanced than just fan units in the seat though... 
Had it, loved it!
2007 Vogue SE TDV8
Stornoway Grey / Ivory
Climatic Seats, RSE, AFS, Deployable steps, iPod kit.

I'm a bit confused about this. If the cooling is only a fan drawing cold air from the A/C, does that mean that when it's heated, there's an element that just heats the cold air that's been drawn in as per the cold setting? Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey

I don't understand it like that. It will draw air into the unit from the cabin, whether air conditioned or not.
The Peltier cell then applies heat or cooling to that air. The fan units then push the air through the perforations in the leather.
Sorry if my last post was confusing, what I was trying to say is, if you start with cooler air in the cabin (e.g. Air con set to cold) then the seat unit adds additional cooling the effect would be either colder air from the seat or decrease in the time it takes to achieve the cooling effect?
That's probably now as clear as mud?  
Had it, loved it!
2007 Vogue SE TDV8
Stornoway Grey / Ivory
Climatic Seats, RSE, AFS, Deployable steps, iPod kit.

Yeah!  Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey

It's using a Peltier cell that takes advantage of the Peltier effect. Without getting too into it different voltages applied to the cell will cause it to either emit heat or draw in heat. This means in the FFRR it can heat up to about +10-15 degrees and cool about -6-8 degrees. 
07 Supercharged - Still breaking her in!

Boot soundproofing part 1 - http://www.fullfatrr.com/forum/topic15612.html
Custom exhaust - http://www.fullfatrr.com/forum/topic15296.html
18" wheels for Brembo equipped cars - http://www.fullfatrr.com/forum/topic15052.html

Hi all,

I cant find if this has been continued elsewhere.

During the last cold snap i've discovered that my drivers seat has refused to heat in both the base and the back. When you switch it on, you can hear the fans start to run for about a second then switch off.

I tried it on cooling and the fans continue to run but maybe there's a setting that if the cabin is 2 degrees it will not activate the pelter cell and add additional cooling.

As it's finally stopped raining out there I'll see if I can do a little bit of extra diagnosis on it.

A quick search shows replacement units are about £350 each and you need two - one for the base, one for the back! !

I Next step will be to try and read the fault codes I guess - it's bound to have an ECU.....