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This where I think we started.... assuming this was correct. And that the overall compressor system is the same in both.
That hardware in the rear is suspicious....
We're all operating on little data, but, with one (say) compressor being strong enough to cool the battery (which is a lot of heat under supercharging), I would think it could be enough to cool the 6/7 without an additional 'back seat' compressor.Compressor possibly being the same does not mean the rear HVAC would just be an extra controllable fan, though. With two more vents and software controls for the third zone there could be some extra hardware in the trunk...
The diagram in Post #34 identified the A/C compressor, the battery heater and the cabin heater, so the HVAC component at the rear of the car wouldn't be any of those. But the second drawing in this post make that rear component look like it includes a fan assembly of some sort.That rear HVAC component does seem fairly beefy. A second compressor? Heater?
He said high 90's, not high 80's. But he also said it was dry. The A/C is much more effective when the air is dry. I've only been there once and a very long time ago, is Dallas/Ft. Worth a dry climate?
Ironically just yesterday my X was at the service center and I asked them to explicitly check the airflow to the rear vents. Both the service advisor and technician there when I dropped off my 5-seater agreed the air flow was very weak. Unfortunately this was the result of their investigation:
View attachment 224677
I spoke with the service advisor afterwards and asked that he escalate the issue BEFORE everyone gets to the worst of summer high temperatures. I understand that every turn of the conduits to the back vents creates some "resistance" to the airflow so the air coming out the back will be a bit weaker, but it's disappointing at the least. I lived in Austin for many years before moving to IL so I share essmd's concern. I'm now going to look into proactively adding one of the heat reducing films (Spectra Photosync, Llumar, etc.) much like essmd.
I will *nicely* continue to follow-up with my service center to have them make sure "corporate" investigates the issue, and that's my best recommendation for anyone else. I fear nothing can be done (they're certainly not going to put wider conduits to the rear vents), but it's worth getting the right people to think of a creative solution. At a minimum if the right people don't hear from enough people, they won't even try.
The diagram in Post #34 identified the A/C compressor, the battery heater and the cabin heater, so the HVAC component at the rear of the car wouldn't be any of those. But the second drawing in this post make that rear component look like it includes a fan assembly of some sort.
How's this for another wild supposition? That HVAC component in the back could be an evaporative coil together with a fan. Analogous to the inside unit of an A/C split system in a house. The compressor coolant is pumped from the compressor to this evaporative unit, which with the blower, sends the cool air to the rear seat vents. This location for the HVAC component would then make sense since this location is closer to the 2nd and 3rd row seat vents. There's no need for a second compressor in the rear. Remember that this diagram only shows high voltage lines, not coolant lines.
One way to confirm this would be to see if there is condensation dripping unto the ground in this area when the rear AC is running on a humid day. I can see having a separate evaporator coil for the front dash vents because they would have a large load from the big windshield and preference to the front seat conditioning. This layout would be efficient because if there are no rear passengers, no fan OR cooling energy would be spent to cool the rear of the car, and the front evaporator would always have the same load whether there were rear passengers or not.
What do you think?
Y'all can speculate all you want, but I know the facts cause for over a year I obsessed over the A/C system.
I was supposed to get my '16 MX in April, but because I was concerned about the A/C effectiveness, I delayed my build until I had feedback from others in the Az heat that the A/C was adequate for an EV and a SUV cabin, plus some local testing of my own in June.
There is only one compressor in all Model X's, confirmed by direct discussion with service techs. The only difference between the 5 and the 6/7 is the 2nd rear fan and the ducting.
Model X Emergency Respond Guide said:Model X has one charger located inside the left-hand side quarter panel. This charger converts AC current from a charging station to DC for charging the high voltage battery. It also routes high voltage to the rear HVAC, if equipped. The high voltage junction box, integrated into the charger, routes any surplus energy from regenerative breaking back to the battery.
How do you know there is no refrigerant line going to the rear HVAC assembly? The emergency guide only addresses high voltage components. A refrigerant line poses no danger by severing, so there's no reason to locate on the diagram. I don't know that there is one, I'm just saying we can't make the assumption that there isn't because one isn't shown on the high voltage components diagram.Been reading about this and apparently here are roughly four different types of HVAC modules:
1) just a blower/fan
2) blowers with temperature actuators, i.e. motors cutting cold/heated airflow as needed
3) blowers with above, plus an extra heater
4) blowers with refrigeration lines running to them basically creating front and rear A/C with just one compressor (e.g. Jgrogville's suggestion)
Since there are no refrigeration lines shown in the emergency guide, and given @essmd's information, I find the 4) not likely. Number 2) seems very likely to me, I can't see how it could be just 1) and make a third zone. Number 3) we have no information on, just noting the possibility given the high-power line.
Here is one car with refrigeration lines going to back, but just to clarify, there is no reason to believe this would apply to Model X:
OK, the Model X Emergency Respond Guide does confirm the "rear HVAC" component is optional. Thus suggesting that is a part 6/7 seaters have and 5 seaters do not. So it IMO would not seem to be a drivetrain component as some suggested. It also confirms high voltage power is supplied to the rear HVAC (on the right side of the trunk) from the junction box integrated into the charger on the left side of the trunk - as shown in the images in messages above.
If that is just a fan, it would seem to be quite a beefy fan!
Here is a picture of the Model X rear HVAC assembly:
View attachment 224785
Yeah, tell me about it... if not, at least it gave its life for a good cause!Great detective work @Jrogville & @AnxietyRanger. I'm on the edge of my 2016 Model-X vented seat.
That was a painful series of photos to watch @boaterva. I hope that started as a totalled X.
I hope that Tesla can reconfigure the fan speeds to compensate for this, but once again the Tesla Design team failed to think outside of their "California Box Mentality", and chose to remove the rear fan from a medium-sized SUV just because there was no 3rd row passengers... A BIG MISTAKE to many owners.
...as when Lexus dropped the GX from a V8 to a V6...
How do you know there is no refrigerant line going to the rear HVAC assembly? The emergency guide only addresses high voltage components. A refrigerant line poses no danger by severing, so there's no reason to locate on the diagram. I don't know that there is one, I'm just saying we can't make the assumption that there isn't because one isn't shown on the high voltage components diagram.
I tried in vain to get the sales manager to allow me to order the "opttonal rear HVAC." but sadly that "option" did not present/nor was it allowed on a one off-no surprise on the latter. Maybe, just maybe, that will be a future option...
Thank you very much
FURY