I checked my sunroof drains. All four were fine. I then felt under the rear nearside carpet in the passenger footwell. It was absolutely saturated, not just damp or wet but totally drenched. The nearside front footwell carpet was the same
I removed the rear carpet and the weight of it! I then removed the front passenger seat and lifted the carpet. I could have kept fish in the footwell! My aqua-vac sucked up a good pint of loose water. Citroen may have done a wise thing to put impermeable carpets in the Xantia to prevent top spills soaking through but it very effectively hid this problem for a long time and I'm staggered at how much water the foam backing on the carpets soak up
The source? I think I have been a muppet. For all the time I have owned the car, the front nearside mudshield has been missing under the front wing. I did not think it would be a problem but I think I'm wrong. The heater air intake drains from a big hole under the wing and the hole is normally covered by the mudshield. leave it uncovered and spray has a direct path into the air intake, into the heater and then straight into the floor-pan! I proved this with a watering can. Also, all sorts of crud ends up in the drain hole, just making the problem worse.
So, the moral of the tale is don't leave mudshields off!!! Now I need one urgently as the car is presently off the road, seats and carpets out, whilst I patiently wait for it to dry right out. It's not moving until a mudshield is in place.
Does anyone reasonably local to Milton Keynes have one I could have as Xantias are very scarce in local breakers. Alternatively, is it possible to make one from a sheet of suitable plastic, even as a temporary expedient? There is no way I want to go through having all the carpets out again!
I still think have a little leak on the tailgate seal causing water in the rear seat wells but compared to this, it is nothing!