Weak heater on a 2018 model 3

[chracatoa]

I always use AUTO but this month it doesn't seem to heat to the temperature I set. I usually like it at 70F or so, but even at 75F is still cold. I mean, not COLD cold, but definitely a few degrees below 70.

Not sure for how long this has been happening because only now it's getting a bit colder.

The car is actually warmer when I get in because I pre-heat it, but then as I drive it becomes a bit colder. Not by much (I'll try to measure it exactly tomorrow). So it seems like a software issue. This car doesn't have a heat pump.

Also, I noticed that no air is coming out in the back (although that may have been true before, I just never needed to check it).

I'm a bit worried when it gets really cold outside. Right now the coldest we got was 30F.

 

[Birdsfan]

I can control the rear climate, including on/off, in my 2021 and I assume you can too. Regarding the rest of your post I would suggest putting in a service request from the app.

 

[Tronguy]

OK. 2018 M3. That's, like, 5 years old, now.

The cabin air heater in an M3 of that day and age is an honest-to-golly resistance heater, just like the heater one finds in a toaster.

Could be that one or more of the wires in said heater have bit the dust.

As a $RANDOM guess, it could be that the car's fan is stuck on High, resulting in colder air as well.

Car's probably out of warranty, but might want to put in a service ticket. That, or figure out how to get the heater out of the car and test it on a bench somehow. Or determine if the resistance of said heater meets some Tesla specification; if it's too high, probably missing some wires or something.

 

[Big Earl]

Try not using the preconditioning for a couple of days and see if that changes your perception of heater performance during the first ten minutes of your drive. I've found that a previous software version caused some strange behavior when starting a drive after preconditioning.

If you set the temp to HI, does the heater get hot hot?

Another possibility is that you have a bad temperature sensor somewhere in the system.

 

[bbell]

You might want to look at the little screen on your heat control display for an error.

You may have a warning there, you can mention that to service when you open the appointment.

 

[Cgc3405]

I have the same issue now too. My only difference is that my heater broke entirely - stopped producing any heat. I had to pay out of pocket to replace the PTC heater. Now that I have it back, even set to as high as 75 degrees on Auto and Auto Circulate, it's just cold in the car. I brought it in for service, but of course, they are saying there is nothing wrong because their diagnostics didn't pick anything up.

I have had the car 5 years, with no heat issues. It's always be 100% comfortable set at around 72, Auto. Now, it's just uncomfortable unless I put it on HI, and then it gets too hot. Super frustrating, especially since they are saying nothing is wrong. Tesla service leaves a lot to be desired.

 

[stopcrazypp]

I have the same issue now too. My only difference is that my heater broke entirely - stopped producing any heat. I had to pay out of pocket to replace the PTC heater. Now that I have it back, even set to as high as 75 degrees on Auto and Auto Circulate, it's just cold in the car. I brought it in for service, but of course, they are saying there is nothing wrong because their diagnostics didn't pick anything up.

I have had the car 5 years, with no heat issues. It's always be 100% comfortable set at around 72, Auto. Now, it's just uncomfortable unless I put it on HI, and then it gets too hot. Super frustrating, especially since they are saying nothing is wrong. Tesla service leaves a lot to be desired.

Sounds like a bad temp sensor somewhere.