Tried searching the forum for this, but no luck. Both front seats in my 2008 HSE are suddenly in heating mode while NOT being switched on at all. A/C system is on, in auto recirc mode, as it's been for almost eight years of ownership. Brand-new A/C compressor put in this spring. Seats now stuck in heat mode. Had the stepper/blend flap clicking sound behind the dash for a few months, but that's gone away. Any ideas?

Sounds very odd.

I would suggest plugging an obd tool in to read the codes. It could be the heated seat module has lost communication with the body control module, or something similar.

The heated / cooled seats don't stay in a mode with ignition off, they need to be commanded to heat / cool again after ignition on.
I would have expected the heated only seats to be the same.

I would be tempted to pull the fuse, or up, ug them until I got chance to take a look at them.

Good luck with figuring out what it is. Too many toys, not enough time

2011 4.4 TDV8 AB Black

All good thoughts, John. I have the heated/cooled seats, both front and rear. (I wonder if the rears are putting out heat; I'll check.) I'm going to see my indie LR guy next week. He's got all the right OBD tools. I'll likely pull the fuse(s) or unplug them in the meantime, as I don't need any extra heat on these 100-degree summer days in Dallas!

Do the switches still work? If they are heating up, does the switch light up to say they are heating? What happens if you turn the dials/switches?

I would start with a battery reset as the seat heating ECU maybe in distress/stuck! And a battery reset might reset it

If they are heated / cooled then I am even more surprised.

As Craig says, do the knobs work to switch from heat to cooling ?

Are both the back and base getting hot, or just one of them ?
You should be able to select back only, which would potentially tell you if the module is receiving the switch commands.

You should be able to hear the fans running under the seats too.

FYI obd can read live data for the switches, so can tell if they are being read properly.

The rear seats are a different control module, so if all 4 are on that would be even more odd. Too many toys, not enough time

2011 4.4 TDV8 AB Black