100 series ca it heater problems

[Ron t]

Need help
my 100 series has a problems with the cabin heater
heater works fine if ambient temp about around 8 c if any colder the heater stops working , water pipes etc still hot , elect diagram shops an external ambient temp sensor but have not been able to find this to test it, has anyone had this sort of problem before
thanks
Ron

 

[uHu]

There is an ambient air temp sensor behind the bumper.
There's a "sun sensor" on top of the dash (little black knob).
There's an internal (room) temp sensor under the dash, behind a tiny little grille in the panel above your legs. There have been reports of this sensor falling out of it's hole, and instead feel the temp coming out of the floor/feet vent.

 

[Ron t]

Thanks very much for this information , reason I could not find the one under the bumper is that it is missing , found the correct plug but sensor no longer there , will get a new replacement and see if this fixes the problem