Heated and cooled seats

I've just joined the forum

 Purchased 2 day s ago an XF 3.0S Portfolio. 119k on the clock. Engine tuns like a dream. A few issues as expected.

I'm getting the air con checked but have issues wirh intermittent cooling operation of the seats. Sometimes a blast of cool air from the seat, sometimes not. I guess it's a separate system from the standard air con unit in the engine bay, or does it work doing this? Any suggestions would be appreciated.

Previously owned an XJ6, then an XJ12 then 3 x XJR supercharged. 5 years ago I had an XF 3.0 diesel not the sport which I've just brought. 4 years of driving a company van. Now semi retired and the van has disappeared over the cliff. Not a caravan owner! Also had a nearly new TVR. That was a blast. Rock solid Rover V8 Engine but dodgy electrics and boot fastener!