Xantia stop light + temp light when heater set to windscreen

[ashy90]

Just as the title says really.
On my 2000 W reg Xantia 2.0 HDI, with the heater direction set to windscreen, the stop and heater temp gauge light start to flash together.
Slide the control away from windscreen and it stops flashing.

The previous owner has fitted some sort of automatic thermostat in the top hose which brings the fan on at a certain temp. He done this because one of the two fans stopped working. Would it be something to do with this?

[GiveMeABreak]

Very likely the additional fan speed and and directed heat from the hoses are causing the increase in the thermostat temperature.

[ashy90]

This will happen even when stone cold.

Start it up after being sat overnight, out blower on windscreen and the lights will flash

[xantia_v6]

On a late Xantia, moving the air direction to the windscreen automatically enables the A/C compressor, and tells the Bitron fan controller to enable the cooling fans at low speed. The Bitron controller is probably detecting a fault due to the hacked wiring.