Car model and year:
Peugeot 406 hdi 90
Have problem with the temperature of the air coming out of the heater/aircon. Firstly the air is either hot or cold. It doesn’t mix at all. Secondly the auto function seems to do nothing.
Peugeot diagnostic tool advice:
PP2000 Peugeot diagnostic tool, I recommend obd365:
Optional solution for reference (1):
One technician who had the similar problem with me, he did like this.
I ran it on PP2000 Peugeot diagnostic tool and all the sensors show sensible values but the heater continues to ignore them ( reading of 12 degrees in the car, engine warmed up, control set to 22 flap position remains on cold, reading 24 in the cabin, control set to 18, flap remains on full hot )
I sourced a replacement control panel (thanks Kelv) which seemed* to fix it for a while but it is back to its old tricks again. The system only has 3 positions as far as I can tell on PP2K hot, cold, and mix. Sometimes I can get by leaving it on 24 which seems to make it stick at mix, but most of the time I have to stick it up to 30 to get noticeable heat, then back to 14 when it gets too hot. If I don’t go to the these extremes and drop from 30 to 20, it just sticks on hot.
The latest theory is that the actuator/flap is sticking, and will only move when asked to go fully one way, rather than half way. The actuator test in PP2K seems to only move it all the way, top to bottom, with a note when it is in the middle, rather than hot [stop], middle [stop] cold [stop] so I cant actually test this and I haven’t had the inclination to take the dash apart to try a replacement motor / test how free the flap is. This would make sense, if it has only 3 settings, as it must dance quite a lot to keep a stable temperature.
Auto “not blowing much” seems to be the norm. It seems to not like making a racket and would rather warm you up slowly (though I may yet be corrected on this)
Optional solution two for reference (2):
swapped over the interior sensor and also control panel with no change to how it worked, in the end i found a setting in PP2000 Peugeot diagnostic tool where there were two modes of operation for the system, I changed it and it’s been fine ever since.
(I’ll have to load up PP and remind myself what option it was)
I did test it on another 406 where i changed the modes and effectively recreate the same problem.