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Model s 85D 2015 won't heat

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Bulisti

Member
Jan 6, 2022
17
0
Helsinki, Finland
#1
Hi!

I am new at this forum, and I tried to use search, but didn't got answer for my issue.

To the problems:

I got 2015 year tesla model s 85d. I have issue with the AC. I live in Finland, and we got around -15c temperature here, and my car doesn't warm up. AC blows only minute warm, and then it starts to blow cool/cold. Sometimes it blows warm again like a minute, then back to cold. I have warm garage at home and at work, so car isn't frozen etc.

I have tried booting with steering wheel and i have also tries wheel configuration. No difference.

We have about 4 weeks que to Tesla Service, and I need my car daily, so does anyone have had same kind of issue? any magic tricks how to make it work?

Hopefully u guys understand what i tried to say :)
 
#2
do you get any errors on the screens when it fails?
Also with it being that cold its possible the car is heating the battery, you say its in the garage what's the temp of that space? Does it do this while sitting in the garage or only while out driving?
I was driving around in California last weekend and when the outside temp got down to -14f (-25c) the heater was still working but it did get weaker and the air it was blowing was not nearly as warm as it was when it was only 8f (-13c) outside because it had to divert more power to heating the battery
 
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Reactions: David29
#3
airborne spoon said:
do you get any errors on the screens when it fails?
Also with it being that cold its possible the car is heating the battery, you say its in the garage what's the temp of that space? Does it do this while sitting in the garage or only while out driving?
I was driving around in California last weekend and when the outside temp got down to -14f (-25c) the heater was still working but it did get weaker and the air it was blowing was not nearly as warm as it was when it was only 8f (-13c) outside because it had to divert more power to heating the battery
Click to expand...
No errors on screen etc.

Grarage is at lowest +5c. I got warmer garage at work, about +18c and still does the same. There was only +6c inside the car after driving for 50km. About month ago, we had as cold as now here, then it was working perfectly.
 
#4
Bulisti said:
No errors on screen etc.

Grarage is at lowest +5c. I got warmer garage at work, about +18c and still does the same. There was only +6c inside the car after driving for 50km. About month ago, we had as cold as now here, then it was working perfectly.
Click to expand...
odd, it sounds like you have parts on their last legs, I'm assuming you've done a brake pedal reboot, if not try that first. if its still acting up do a super reboot as i describe below.

Unplug car from any charging cable
roll down drivers window and leave door opened
disconnect 12v negative terminal
unplug firemans loop
let car sit for like 10 min, the MCU screen should be off and the vehicle should be unresponsive
reverse steps and put it back together
when the 12v is hooked back up sometimes the alarm goes off so have your fob ready to turn it off it it starts honking at you.
the car will take a couple minutes to fully reboot and then test to see if the heater is working properly. if its still acting up then you're prob gonna have to make an appt with tesla to get it checked out.
 
#5
I'm not sure if I have done brake pedal reboot? how it is done?

I have done reboot by pressing steering wheels scroll buttons together for 10 seconds, and also I have done wheel configuration.

I am not sure if it is coincidence, but when it blows warm for the minute, there is no dashed line in battery/voltage meter. But when warm ends and it starts to blow cold, there comes those yellow dashed lines.
 
#6
The “reboot with brake pedal” is the same as the steering wheel reboot, except you need to hold down brake pedal during the button salute. But you mentioned changing tires on the menu so this is well deeper restart.
Before you start to take the car appart, try this. Can you turn the cabin heating on remotely, there is section on the app? It’s advisable during winter time. This will give you understanding that your AC system is functioning OK.
I had an issue last year and it did not started to warm the cabin at the end (preheating before my drive). I let Tesla to look into this and it eventually became a right hand side condenser core change as it was punctured by road debris. My car did not acted differently, my actual consumption got almost 50% better than before. It all resulted quite uncomfortable cabin if the outside temperature was higher than 20°C as the whole AC system was drained empty.
Terveisiä edelästä!
 
#7
AC works fine. I always use app for pre-heating/defrosting. Now it just doesn't warm up, but fan/seat warmers works normally. We have about month que for SC here in Finland, so it is little difficult to drive when windows freezes while driving and also it very cold in car.
 
#9
I had something similar happen in my 2013. I know they changed this design at some point and am not sure if it still applies to the 2015s, but within the DCDC there was a fuse for the PTC heater. The fuse blew on my car and had to be replaced, which was handled in a mobile service. There was similarly no indication on the display that anything was broken. Same symptoms you have.
 
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#10
airborne spoon said:
do you get any errors on the screens when it fails?
Also with it being that cold its possible the car is heating the battery, you say its in the garage what's the temp of that space? Does it do this while sitting in the garage or only while out driving?
I was driving around in California last weekend and when the outside temp got down to -14f (-25c) the heater was still working but it did get weaker and the air it was blowing was not nearly as warm as it was when it was only 8f (-13c) outside because it had to divert more power to heating the battery
Click to expand...
Wait, what? Where would it be -14F in California!? Up in the Sierras, maybe? not doubting, just startled.
 
#12
David29 said:
Wait, what? Where would it be -14F in California!? Up in the Sierras, maybe? not doubting, just startled.
Click to expand...
Yeah up north in the real California not that *sugar*-hole desert known as So-Cal 😎😂
the example was from a trip last weekend I was driving through Bridgeport. But the whole morning was in the single digits on both sides of 0f

P_20220101_080524.jpg
 
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#13
Gizmotoy said:
I had something similar happen in my 2013. I know they changed this design at some point and am not sure if it still applies to the 2015s, but within the DCDC there was a fuse for the PTC heater. The fuse blew on my car and had to be replaced, which was handled in a mobile service. There was similarly no indication on the display that anything was broken. Same symptoms you have.
Click to expand...
Do you have any idea where the fuse is located?
 
#14
Bulisti said:
Do you have any idea where the fuse is located?
Click to expand...
It was inside the DCDC. The technician had to tear apart a good bit of the car and open up the DCDC itself. It's high voltage work, so probably not recommended for customer replacement. At one point it looked like half the "engine bay" was sitting in my driveway.

He said I was lucky in that he could just replace the fuse and that when some of them fail it takes out part of the DCDC itself and the whole unit needs replaced.
 
#18
Bulisti said:
forget to attach link: Tesla Model S (2015)- fuse box diagram - Auto Genius

btw: there was two visible fuse boxes under the plastic trim in frunk. There was no heater fuse, is there another fuse box like in link. or is that fuse box in link, the one i should let SC do?
Click to expand...
No, this box on the photo (attached on top of battery) is the fusebox that is recommended to service by SeC. The one in the link should be in the frunk bay, maybe it’s hidden in 2015 model but on my 2016 its right in the middle under the plastic trim you mentioned.
F87FB111-734D-4808-8548-0DAD37AD8F96.png
 
#19
KalJoMoS said:
No, this box on the photo (attached on top of battery) is the fusebox that is recommended to service by SeC. The one in the link should be in the frunk bay, maybe it’s hidden in 2015 model but on my 2016 its right in the middle under the plastic trim you mentioned.
Click to expand...
That is no longer the case. The huge DC/DC converter is not used they changed the design in 2014 sometime along with the removal of the fuses on top of the battery. Now the converter is behind the front motor mounted to the firewall but it had no replaceable parts and the fuses are now in the 3rd fuse box in the frunk.

There are 2 boxes that are right in front easy to see the 3rd fuse box is slightly back and to the left and a bit tricky to get to but still pretty easy. You can see in my picture it's location

P_20220109_074400~2.jpg
 
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