Erratic heater

[Michael Oakes]

2019 model 3 LR issue on recent 250 mile trip…. The heater has a mind of its own. Can’t seem to find a rhyme or reason to it. Can be cold air when set to max temp.
For most of the trip my feet were cold, otherwise it was ok. Sometimes temp was really high despite being set at 22…. Sometimes cold air when set to anything between 22 and max…
Tried every combination of settings possible 15 times! Lol

Any air directed at feet was always cold.

There was long periods where cool air was getting blown at me… but it was -1 outside, if the heater wasn’t working at all i would have been freezing…. I was just a bit cold. 10 mins later i was too hot. It was cold much more often than hot.

Pre-heating car twice at services it was spot on 22 degrees both times and got there quickly.

Anyone had similar or can suggest a fix? The heater is clearly working - when its hot its really hot.

 

[KalJoMoS]

Have you tried to use manual settings, I have never used it on auto? Been now fifth winter in a row. Non of that experienced, but I have an S…

 

[GtiMart]

Did you look at the service menu to see if there are any error messages there that could help you diagnose? If the heater core generates plenty of heat then it's probably not the culprit. The next things I would wonder about are the temperature sensors: one inside the cabin (under your center screen) and one outside somewhere in the front bumper. If these provide wrong values, the car would probably not take the right decisions.

 

[Gtech]

Otherwise you could check SMT for some temperature data, here is mine set at 'auto' and 19 Celcius

In my car when 'auto defogging' is on feet are frozen (because it only heats the front window) but as soon and the HVAC returns to normal 'auto' mode temp is set to normal and feet are warm

 

[wtlloyd]

I had a similar problem with my '23 Model Y LR after a couple months. It was a defective cabin temperature sensor.
Easily repaired at no charge.