Heat / HVAC on 7.0 - poor performance?

[scaesare]

A quick thought on this:

With the introduction of v7, many of us saw a ~10% reduction in driving energy usage reported on the dash. For me, I was still able to make my morning commute at under 300Wh/mi, despite temps starting out in the high 40's and ranging in to the 50's. Previously that had been impossible for me, as even with conservative driving, as it appeared pack heating would burn some juice.

Now, that appears to no be as aggressive. Coincidentally, the cabin heating appears to be wonky as well.

We know the cabin and drive-train thermal systems are tied together[1]. I wonder if an attempt to optimize on affected the other?

[1] Although I believe the cabin air heaters are free-air PTC heating elements, not coolant heaters as they are for the pack.

 

[mknox]

With the introduction of v7, many of us saw a ~10% reduction in driving energy usage reported on the dash. For me, I was still able to make my morning commute at under 300Wh/mi, despite temps starting out in the high 40's and ranging in to the 50's.

Not me. I watched this like a hawk since I got v7 and could not discern any change. No better, but no worse. The release notes said that 2WD torque sleep was supposed to help, but it doesn't seem to in my case. It could be because my 45 mile (each way) commute is mostly freeway with little start/stop along the way.

The HVAC has been totally nuts, however. It seems to turn the heating elements on quite high, but operates the fan speed quite low. Usually around 2 but sometimes 3. So low that I get a burning smell from the heating elements I'm assuming because there isn't enough air flowing over them. If I manually bump the fan speed up, it works better... for a while. Eventually, the cabin starts to get noticeably cooler after having warmed up initially quite well, and then I have to start bumping the temperature up.

This morning, it was 25 F out. Same thing. Fan speed of about 3 on Auto and burning smell. I don't know why it doesn't start out with the heat on high and the fan at at least 8 or 9 to quickly warm up the cabin, then throttle it back. This is how every other car I've had with automatic HVAC has worked.

 

[scaesare]

Clearly both behaviors are not consistent across the board for everyone... or even for a single car. My heater seems fine on some occasions, and sub-par on others. Some have reported energy usage reductions, others don't.

So who knows what other factors are in play, but I do find my apparent less aggressive pack heating and my less aggressive cabin heating to be an interesting coincidence that showed up with v7...

 

[cwave1]

I finally got my car back after 8 days at the Mississauga service centre. I had a lengthy list of items to fix but I think the heat problem was fixed within 2 days. I have other items that still require a return visit (drive unit, winter brake package, rear suspension clunking, headliner replacement due to pano leaks).

Here is what the work order shows was done to fix the heat issue:

Corrections: DC-DC Converter - 1st GenerationReplaced
- DC-DC converter that was causing no heat condition.

Part Quantity
DCDC CONVERTER ASSEMBLY (6009170-00-J)1

 

[bart513]

I'm new to the MS and the heat was on with the AC - also my kids were cold for some time as the rear vents were giving cold air for 5-10 minutes and the air flow was very weak. I have a 2015 MS 85D

 

[bhuwan]

I am starting to notice poor HVAC heat now that the weather is getting cold. Is this a firmware issue?

 

[jerry33]

I am starting to notice poor HVAC heat now that the weather is getting cold. Is this a firmware issue?

As far as I can tell, yes. It wasn't that way last winter. New with V7.

 

[scottm]

V7 should have included a button in HVAC called "Randomize" or "Shuffle" ... because that's what we're getting?

Is it my imagination that at the end of the long decel / regen.. the cabin heat blows a little hotter than steady state driving? Like something is trying to shed heat in regen process, and if HVAC heating is on, then heat gets dumped into it... This is happening when the battery still shows a "cold" line where max regen has been reduced. Wonder if excess spills over to HVAC electric coils somehow... I dunno. Wishful thinking !?

 

[Peter_M]

I finally got my car back after 8 days at the Mississauga service centre. I had a lengthy list of items to fix but I think the heat problem was fixed within 2 days. I have other items that still require a return visit (drive unit, winter brake package, rear suspension clunking, headliner replacement due to pano leaks).

Just curious... what's a "winter brake package"?

 

[cwave1]

Just curious... what's a "winter brake package"?

I've had my rotors start vibrating for the second time after last winter. Tesla mentioned that in cold climates like ours where salt is used on the roads, the salt pits the rotors and causes them to warp. They have a new design for us that they are installing under warranty.

 

[mknox]

I was at my local Service Center today, and the manager there asked me how my heat was working. It seems he had been getting a lot of complaints. I told him (won't repeat again here). He said Tesla's intent with the lowering of the fan speed was that the elements could radiate more heat without as much air flowing over them, and that a slow warm up of the cabin is more efficient than a fast one. He kind of agreed with me that in colder climates, sometimes more airflow is necessary to prevent window fogging and such. My suggestion to him was to move this new algorithm over to the "Range Mode" setting and leave "normal" HVAC operation alone.

 

[jerry33]

I was at my local Service Center today, and the manager there asked me how my heat was working. It seems he had been getting a lot of complaints. I told him (won't repeat again here). He said Tesla's intent with the lowering of the fan speed was that the elements could radiate more heat without as much air flowing over them, and that a slow warm up of the cabin is more efficient than a fast one. He kind of agreed with me that in colder climates, sometimes more airflow is necessary to prevent window fogging and such. My suggestion to him was to move this new algorithm over to the "Range Mode" setting and leave "normal" HVAC operation alone.

I used the defogger for the first time this winter today. Put it on the second level (red) and cold air blew out. The car was preheated before driving. I'm not impressed.

 

[trils0n]

I am noting that the max defrost (red) no longer always puts the fan speed to max like it used to. Sometimes it hangs out around 8-10 instead of going to 11. Weird changes. (Does this in both .56 and .77). .77 seems to be slightly better than the initial release -- I only had to put the temp to 77 instead of 81 to get it to blow warm (not hot) air. Not happy with heater performance.

 

[AWDtsla]

I've had my rotors start vibrating for the second time after last winter. Tesla mentioned that in cold climates like ours where salt is used on the roads, the salt pits the rotors and causes them to warp. They have a new design for us that they are installing under warranty.

Salt does not "warp" rotors. Clearing the brakes after the have rusted over due to being wet or salty while not letting them heat up, and occasional heavy braking with cool down is necessary to keep the braking surface smooth. When people say "warp" what they really mean the the surfaces is contaminated with uneven rust or brake pad deposits. Of course, cars that are not in California often see wet or corrosive environments, and don't get cleared because the car won't do it automatically, and the owner doesn't know any better. Yet another reason to have a regen disable button.

 

[cwave1]

Salt does not "warp" rotors. Clearing the brakes after the have rusted over due to being wet or salty while not letting them heat up, and occasional heavy braking with cool down is necessary to keep the braking surface smooth. When people say "warp" what they really mean the the surfaces is contaminated with uneven rust or brake pad deposits. Of course, cars that are not in California often see wet or corrosive environments, and don't get cleared because the car won't do it automatically, and the owner doesn't know any better. Yet another reason to have a regen disable button.

I'm only communicating what Tesla told me. Your point is valid and probably correct but the good news is that Tesla is taking care of these issues as they learn more about the car in different climates and with different driving habits (like trying to never brake which many of us Tesla drivers prefer).

 

[AmpedRealtor]

I'm only communicating what Tesla told me. Your point is valid and probably correct but the good news is that Tesla is taking care of these issues as they learn more about the car in different climates and with different driving habits (like trying to never brake which many of us Tesla drivers prefer).

Or, Tesla could do what every other auto manufacturer does. Test the car under different conditions and don't depend on your customers to do it for you. Tesla creates something and just throws it out there, leaving owners to solve problems for the company. This is not a sustainable model from a company who wants to further sustainable transportation.

 

[bhuwan]

Wonder if there's a solution for this or will Tesla wait until I freeze to death in the car?

 

[Andyw2100]

I was at my local Service Center today, and the manager there asked me how my heat was working. It seems he had been getting a lot of complaints. I told him (won't repeat again here). He said Tesla's intent with the lowering of the fan speed was that the elements could radiate more heat without as much air flowing over them, and that a slow warm up of the cabin is more efficient than a fast one. He kind of agreed with me that in colder climates, sometimes more airflow is necessary to prevent window fogging and such. My suggestion to him was to move this new algorithm over to the "Range Mode" setting and leave "normal" HVAC operation alone.

That's not really a great solution either, as some of us are choosing to always drive with range mode on in order to maximize the benefits of torque sleep. While we recognize that doing so means we get somewhat less energy devoted to HVAC, dumping whatever this new setup is into range mode and thinking that is a solution to the problem really wouldn't be a great approach. Tesla needs to go back to the drawing board on this.

As an aside, I'm not sure I've noticed this new issue, but then again, I never use any of the "automatic" HVAC functions. I just set a temperature and a fan speed manually.

I've had my rotors start vibrating for the second time after last winter. Tesla mentioned that in cold climates like ours where salt is used on the roads, the salt pits the rotors and causes them to warp. They have a new design for us that they are installing under warranty.

New as of when?

Any idea how they are communicating information about this to those affected?

 

[cwave1]

New as of when?

Any idea how they are communicating information about this to those affected?

I first went in to my SC and heard this diagnosis in May 2015. I don't think Tesla is contacting people proactively. If you go to service and have warped rotors and are in a cold climate, they will replace them. I also heard that Tesla does not machine rotors. I don't think they even have the equipment for this at the SC.

 

[mknox]

I used the defogger for the first time this winter today. Put it on the second level (red) and cold air blew out. The car was preheated before driving. I'm not impressed.

Noticed the same thing myself: One tap (blue) just directs air to the windshield without affecting temperature or fan speed. Two taps (red) directs air to the windshield, bumps the fan up high and shows the temperature settings (both left and right) as HI... but the air coming out is no longer hot. Wonder why???