Hello everyone, I'd like to tell you a story that is driving me nuts.
Last year my A/C just worked on full cold and full hot: we cheked the codes and we found the code 15 (Heater matrix temperature sensor - JLM11948).
Replaced the sensor, charged the system, cleared codes, and everything worked ok.
Last week after one year, strange behaviour: sometimes, when the climate is set on a fixed temperature let's say 23, suddenly fresh air stopped, it started blowing hot hot hot air for a few seconds and then settled on a warmish/coldish average temperature. To get cold temperature and stop the hot I must immediately turn down the temp of 2-3 degrees as soon as I feel it happen. Checked codes once again: error 15 as before!!
This seems to happen much more frequently when it is set on AUTO rather than manual use.
Replaced the sensor once again 2 days ago with a new one, cleared codes to 0 but no difference: climate works ok for a certain time but suddenly gets crazy, blows hot and gets back to cold, and everytime it does this stuff the error 15 pops up; but now the heater core sensor is brand new!!
Another thing I have noticed is that sometimes when going from cold to hot, let's say 18-27 it is really really slow to get to hot temperature!
Tried to clear codes, hard resets ecc nothing works! It is strange though because when on hot and cold it works and it shifts temperatures between them.
Please please help! Thank you!!

 

The temperature sensor you have been replacing is it the one under the front bumper cover. The one out there is the ambient air temperature sensor. It will cause the interior temperature to do crazy things because it senses the wrong outside air temp.

 

Thank you for the answer!
Actually the one I have been replacing twice and that keeps me giving the error No 15, is the one next to the heater matrix: part number 3 in the attached picture.
Looking at the Denso error list, the one you are suggesting, should give me error number 12 on the panel, but that never appeared on my screen and, still acoording to the panel, the external temperatures information appears to be coherent with reality
Still would you suggest that one anyway? That outside ambient temperature sensor is only a bit more then 20 $ Thanks a lot!!!