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Recent heat pump failures - software issue?

After driving from Vancouver to Kelowna in our new Y (two weeks old), our heating failed halfway home, resulting in us having to drive 4 hours with no heat at all. Temperatures were between -5 and -7 Celcius in the car and about -20C outside. Same error message VCFRONT _a447 as other Model 3 and Model Y owners. Our issues was after the recent 2021.44.25.2 update, but not clear if it is limited to the new version.

Just received the following message from Service:

"This is a firmware issue currently under investigation by Tesla as it was recently discovered due to the recent extreme cold climates. There will be improvements with future firmware update as it is currently being developed. Current mitigations are to precondition the vehicle 30-60 min prior to departure, use recirculating air model and use auto mode. Symptoms may still occur when driving in climates -15C and below. If heat does not return please park vehicle in a warmer location and allow vehicle to warm up. '

And "A fix is currently being developed by the software engineering team, and there is no ETA on the firmware version fix."
 

Tam

Well-Known Member
Nov 25, 2012
12,132
11,163
Visalia, CA
...-5 and -7 Celcius in the car...

I am not sure how Tesla would fix the nature of the heat pump. In general, it works best when the weather is above 40F or 4C. Once the weather drops below that, its efficiency is suffered.

Considering the nature of the heat pump, it bravely raised the temperature from -4F or -20C to 23F or -5C is quite a feat.

Maybe Tesla would use software to inject auxiliary heat from the motor to help out the heat pump in cold weather.
 
After driving from Vancouver to Kelowna in our new Y (two weeks old), our heating failed halfway home, resulting in us having to drive 4 hours with no heat at all. Temperatures were between -5 and -7 Celcius in the car and about -20C outside. Same error message VCFRONT _a447 as other Model 3 and Model Y owners. Our issues was after the recent 2021.44.25.2 update, but not clear if it is limited to the new version.

Just received the following message from Service:

"This is a firmware issue currently under investigation by Tesla as it was recently discovered due to the recent extreme cold climates. There will be improvements with future firmware update as it is currently being developed. Current mitigations are to precondition the vehicle 30-60 min prior to departure, use recirculating air model and use auto mode. Symptoms may still occur when driving in climates -15C and below. If heat does not return please park vehicle in a warmer location and allow vehicle to warm up. '

And "A fix is currently being developed by the software engineering team, and there is no ETA on the firmware version fix."
I got this VCFRONT _a447 too going through Edmundson NB last week with -17 C and 80 km headwinds. Made a service appointment on 10 Jan but did not get the Tesla service reply message OP showed. Heat was off (1.5 hours) all the way to Riviere-des-Loup Supercharge. Before charging I did a a hail mary and shut down the Tesla by touchscreen (not just an MCU reboot). Came back up, plugged in supercharge and never saw the error message again. Though it was -7 C warmer at -10C in Riviere-des-Loup. Back in mild winter Montreal the HVAC has been working well. I'm thinking to cancel the SC appointment now.
 
I am not sure how Tesla would fix the nature of the heat pump. In general, it works best when the weather is above 40F or 4C. Once the weather drops below that, its efficiency is suffered.

Considering the nature of the heat pump, it bravely raised the temperature from -4F or -20C to 23F or -5C is quite a feat.

Maybe Tesla would use software to inject auxiliary heat from the motor to help out the heat pump in cold weather.
The overall system is designed with a back-up for the heat pump, according to their patent (and some teardowns). Granted, everything from the patent may not have made it into production:

 

Tam

Well-Known Member
Nov 25, 2012
12,132
11,163
Visalia, CA
The overall system is designed with a back-up for the heat pump, according to their patent (and some teardowns). Granted, everything from the patent may not have made it into production...
Thanks for the info. It makes sense now. I thought it only gets heat from the very cold ambient (in this case -20C) but now, thanks to your explanation, it does take heat from more than 1 source:

1) Ambient
2) Battery
3) Drive Unit

In that case, then they need to fine-tune their software to direct auxiliary heat from the Battery and Drive Unit more.

The problem is: Both the battery and the drive unit have been already cold in the first place, just like the ambient air, so re-directing heat from them is of little effect.

I guess that's why the car needs to be pre-heated an hour or more before the drive.

Tesla needs to tell us how long the pre-heating will be effective to warm up both the battery and drive unit in order to supply enough heat for the heat pump as in this thread with -20C.

It sounds good in theory but can the battery and drive unit be as boiling hot as a gasoline engine or an electric resistance heater to supply enough heat for the heat pump in this thread?

Maybe due to the nature of the heat pump and limited heat production from the battery and drive unit, Tesla should have 2 vehicle versions: A heat pump for warmer regions and a resistance heater for colder regions.

Or they just do one version with all factors included: Heat pump, battery, drive unit, and resistance heater.
 
My Model Y has been heating really well in the -30 cold weather we have had for the last week or so.

slide8.JPG
https://cdn.motor1.com/images/custom/slide8.JPG
 

Tam

Well-Known Member
Nov 25, 2012
12,132
11,163
Visalia, CA
My Model Y has been heating really well in the -30 cold weather we have had for the last week or so...
It's great to hear that not all heat pumps fail but others do experience the problem:

 
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Gheks

New Member
Dec 31, 2021
3
2
Edmonton
am in Edmonton. -30 daytime highs here. Has been good all week till yesterday. I Forgot to plug in the car the night before (unheated garage), drove to the supercharger here (30 min precondition on all the way). Charged. for a few errands i noticed the regen dropping out - can tell right away as the car now glides when letting of the gas. Parked for 2 hours, preheated the car 15 minutes. Lost heat in 5 minute.

Got home, plugged it in when the charge cycle was almost complete tried cycling the heater on. The heat pump would come on (very loud). Interior temp would rise to 5 degrees. Pump would shut off. Heater system would be non responsive until left the car and would be back.

luckily i have a heated shop close by - so drove it there last night and parked it.
 
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Gheks

New Member
Dec 31, 2021
3
2
Edmonton
am in Edmonton. -30 daytime highs here. Has been good all week till yesterday. I Forgot to plug in the car the night before (unheated garage), drove to the supercharger here (30 min precondition on all the way). Charged. for a few errands i noticed the regen dropping out - can tell right away as the car now glides when letting of the gas. Parked for 2 hours, preheated the car 15 minutes. Lost heat in 5 minute.

Got home, plugged it in when the charge cycle was almost complete tried cycling the heater on. The heat pump would come on (very loud). Interior temp would rise to 5 degrees. Pump would shut off. Heater system would be non responsive until left the car and would be back.

luckily i have a heated shop close by - so drove it there last night and parked it.
 

Gheks

New Member
Dec 31, 2021
3
2
Edmonton
After parled the Y in a warm shop and fully charged, Drove it the next day in -28 degree temps, Made sure to precondition the car for a least 30 mins. Could here the heat pump labouring a bit but was always able to maintain the heat. The little steering wheel circle would come on while on the freeway, but never lost the regen braking.
 
Knock on wood but mine has been OK so far thankfully. I drove about 120 km in -30°C. Cabin was very comfortable. Does not give me much comfort though to hear of all of these failures. Definitely will not be taking the Model 3 for any road trips with an overnight with the weather like it is now.
 
After parled the Y in a warm shop and fully charged, Drove it the next day in -28 degree temps, Made sure to precondition the car for a least 30 mins. Could here the heat pump labouring a bit but was always able to maintain the heat. The little steering wheel circle would come on while on the freeway, but never lost the regen braking.
Interesting; I'm in Edmonton also, hopefully taking delivery at end of Jan. There is some talk about the heat pump in the other subforums as well. Have to keep an eye out for that.
 

Tam

Well-Known Member
Nov 25, 2012
12,132
11,163
Visalia, CA
Another article while waiting for a software fix:

"
  • Set climate to Auto and set a comfortable temperature.
  • Use recirculating air mode.
  • Pre-condition your car while plugged in 30-60 minutes before your departure.
  • Park car in a warmer location such as a garage to allow it to warm up.
  • Reboot the vehicle and try again (hold down both steering wheel buttons)."
I am not sure what the spec for Tesla's heat pump but in the meantime the quote is:

“Symptoms can occur in climates -15C (5F) and below”
 
Having the same problem with my new model 3, I have found doing a hard reboot has help to restore the system. Also requires many bouts of pre conditioning through out the day if you are parked somewhere cold. Pre conditioning drops the battery at least 5 percent for 30 minutes and if you are on the mobile charger at the end of the day you will likely be at a net loss of range. Hope someone can confirm if 44.30 fixes this issue!
 
Coldfront taking over QC tonight and tomorrow. Just got 44.30 today purposely left my MY unplugged with 70% charge to coldsoak over night low of -19C. Will see if VCFRONT _a447 error rears its ugly head when I run a few local errands tomorrow morning skipping any pre-conditioning other than steering wheel and seat warmer. VCFRONT _a447 was quite unnerving on pre-christmas update firmware travelling far from home in New Brunswick just before Christmas as stated in a previous post in this thread.
 
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Having the same problem with my new model 3, I have found doing a hard reboot has help to restore the system. Also requires many bouts of pre conditioning through out the day if you are parked somewhere cold. Pre conditioning drops the battery at least 5 percent for 30 minutes and if you are on the mobile charger at the end of the day you will likely be at a net loss of range. Hope someone can confirm if 44.30 fixes this issue!
I received the error on Jan 1. My vehicle had heat the day before. Parked it in heated a garage( 10C). Next morning had vcfront a447 error. Have done many hard resets / reboots and the heater will not start. Got the most recent update last night and it still fails. After reboot I can hear the heat pump trying to start after a reboot. It sounds like a boom from a sub woofer , happens 3-4 times and then I get the error. I am pretty sure , in my case , it’s a hardware issue not software. It’s possible a software issues caused a hardware failure and tesla sent an update to prevent future failure.
 
I received the error on Jan 1. My vehicle had heat the day before. Parked it in heated a garage( 10C). Next morning had vcfront a447 error. Have done many hard resets / reboots and the heater will not start. Got the most recent update last night and it still fails. After reboot I can hear the heat pump trying to start after a reboot. It sounds like a boom from a sub woofer , happens 3-4 times and then I get the error. I am pretty sure , in my case , it’s a hardware issue not software. It’s possible a software issues caused a hardware failure and tesla sent an update to prevent future failure.
That's not good. Hoping the software fix I received yesterday will be preventative, but it does look like in your case it was already too late. Let us know what the fix is when you get it back from the service center.
 

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