So frustrated with the HEAT in my model S

[quickstrike12]

I have the same issue. I dont think it's the heater element (or whatever) because when I first turn the car on, it heats up just fine. And as the OP said, if you set to HI, VERY hot air blows out.

Now I'll admit. I LOVE heat. Hot air blowing on my face and feet is perfect. I am NOT a "72 degrees is just fine" guy. I'm a 78 degree with seat heater on 3 guy all the way.

What I think is happening:
Car heats up to set temp. But on reaching that temp, it does not know how to maintain it well. So it blows warmish air and then cooler air to keep temp at set degree.

At some point, all I notice is that cold air is blowing out the vents and I have the heat set to 80 while the temp outside is 64.

I think outside temp has something to do with the "algorithm". When it's 60 or below I dont have this issue. But in that 64 to 68 degree range, the car just doesnt know how to deal.

All speculation but I was commuting last week very irritated at cold air blowing on my face with the heat set to 81.

When it’s in manual mode this is exactly what it will do. Now in Auto it will keep the car nice and toasty. But it is a resistance heater and it’s ability to heat is not linear. The colder the air is the more efficient it becomes. This why on a cool 50 degree day it doesn’t seem to make much heat set at 71 for example. But on a day when it’s 30 outside that same setting makes plenty of warm air. It works differently when it’s in auto tho. Try it yourself. Set to an auto setting and have it coming out nice and warm then change nothing at all but out of auto and the air is cold.

 

[KirkS85]

Crud, I just bought a 2019 Long Range S and this is exactly what is happening.

I also have a 2014 MS and it does not do this. At 72 degrees setting it’s nice and toasty inside.

Anybody ever figure out if this is normal or heater core issue?