How's your AC?

[mknox]

Did you have the AC mount TSB applied to your car? There are two TSBs, one for noise (sound insulating blanket) and one for vibration (revised bracket).

They were supposed to have done both. It is better, even inside the car, but IMHO there is still a fair amount of vibration that I can actually feel through the interior surfaces when it spools up high. Not as much as before. There are those who say an ICE simply masks this, but I could not ever feel any interior vibrations in my previous Cadillac with both the engine running and a/c on.

 

[jerry33]

They were supposed to have done both. It is better, even inside the car, but IMHO there is still a fair amount of vibration that I can actually feel through the interior surfaces when it spools up high. Not as much as before. There are those who say an ICE simply masks this, but I could not ever feel any interior vibrations in my previous Cadillac with both the engine running and a/c on.

I never noticed it while I was the driver, but now that Denise drives the Prius, I can hear the electric a/c compressor from across the street (as we do the driveway shuffle).

 

[mgboyes]

Now I'm really scratching my head.

I set-and-forget the controls, too. In the past two hours, I went out for a drive; observed temps varied from a low of 109ºF/43ºC to a high of 114ºF/46ºC. My AC is set to "Lo", "On", and Recirc.

And it stays nice and comfortable.

Just what seems to be the problem all are mentioning?

??????????????????

Well LO presumably means "throw everything you've got into cooling the cabin" i.e. the car can disregard what the temperature sensors are telling it because it just needs to run at max cooling.

The problem is that if you set the target temperature you actually want (rather than "LO") the car will NEVER make the same sort of effort that it does when LO is selected, and the cabin temperature will never get anywhere near the setpoint you've selected.

Showing that LO is effective is great because it proves that the hardware is capable of cooling the cabin even at 114 ambient. It's just that the control logic that does this automatically doesn't work - which is why you've had to override it by manually selecting LO.

 

[spottyq]

They were supposed to have done both. It is better, even inside the car, but IMHO there is still a fair amount of vibration that I can actually feel through the interior surfaces when it spools up high. Not as much as before. There are those who say an ICE simply masks this, but I could not ever feel any interior vibrations in my previous Cadillac with both the engine running and a/c on.

I do not know how belt driven accessories work with an ICE, but I'd guess that you couldn't run the AC compressor at maximum when the ICE is idling (=> in order to run at full tilt, the AC compressor would need the engine to be in "cruise" rpm, say 2000-3000 rpm at least.)
If that is the case, you would be comparing the lack of vibration of ICE+AC not running at maximum power, versus Tesla's AC working full tilt.

Could this be the case ? (please keep in mind I do not know how belt-driven accessories work; it could very well be the case my hypothesis is false and thus my question moot.)

 

[ny888]

I've been dealing with the same issue having to manually set to LO to get the desired comfort level. Maybe it's my imagination but after having done that a few times, it seems like the auto fan is stronger when my temps are set in the middle 60s. Whereas there was no detectable fan blowing when I set to 68, yesterday I could clearly feel the fan blowing at the same temp.

 

[Ingineer]

Clearly there are bugs in the system. In A/C mode, The system should always use full power fan when there is a significant Delta-T between setpoint and interior temp. The exceptions are unless it's in Range mode (because it has basically been told to slow down), or in the event the battery pack has priority of the system. For example if you are supercharging. In heat mode, it should monitor the output temperature of the PTC heater in the plenum and start off slow and slowly ramp up as the heater gets up to full power. In heat mode you don't want a blast of cold air before the PTC is at full power, and you generally want the minimum airflow that can keep the PTC at peak kW. Any more airflow and it generally feels like a cold draft, so I suspect that in heat mode you'd probably never need to get the fan much over half way to achieve full kW. The only mode in the winter that should invoke full fan is defrost.

 

[AmpedRealtor]

There is too much weight put on the outside temperature. For instance, if the temp is set to 72 and it's in the 80s, it barely blows. But if it's 109 outside, it blows like a champ and cools the interior quickly. Tesla needs to tweak the software, but after two years, it still isn't a priority? Doesn't Musk ever use the climate control?

 

[Ingineer]

This is why all Engineers that work on a product should be forced to use that product. Most Tesla engineers don't own a MS. I think it would pay to at least loan a MS to each engineer, especially those that work on system software.

I know from personal experience, the actual use case vs. the ones I often imagine a end user with are often very different in the real world. The team working on HVAC is going to have a different experience driving the car to work every day vs. testing it in the lab.

 

[beeeerock]

Clearly there are bugs in the system. In A/C mode, The system should always use full power fan when there is a significant Delta-T between setpoint and interior temp. The exceptions are unless it's in Range mode (because it has basically been told to slow down), or in the event the battery pack has priority of the system. For example if you are supercharging. In heat mode, it should monitor the output temperature of the PTC heater in the plenum and start off slow and slowly ramp up as the heater gets up to full power. In heat mode you don't want a blast of cold air before the PTC is at full power, and you generally want the minimum airflow that can keep the PTC at peak kW. Any more airflow and it generally feels like a cold draft, so I suspect that in heat mode you'd probably never need to get the fan much over half way to achieve full kW. The only mode in the winter that should invoke full fan is defrost.

^ this exactly! Delta-T is not being fully respected and there might be a few other more minor logic issues too... but this is the big issue for me.

 

[smilepak]

I wonder if their AC is like the Honda. I noticed in my Honda, I can set it whatever temp, as long it is higher than outside temp, it's warm air, rather than the actual air temp you set it at. So during the winter when outside temp is 72, if I set AC to 73, it blows hot air. but if I set to 71, it blows cold air.

my Lexus on ther hand, AC blows at the temp you set it. If outside is 72 and you set AC to 73, the air still feel cool, not cold to get the cabin to 73..

someone mention ion to me that Tesla AC doesn't use feon? Their cooling system is ceramic based?

 

[Ingineer]

The A/C system in the MS is almost identical to any ICE, except that the compressor is driven by an integrated electric motor from the HV battery, instead of a belt from the ICE. Also, there is an additional cooling circuit that can be used to cool the glycol that runs through the battery pack. It uses the same refrigerants ("freon") that are used in all ICE cars.

The electrically driven compressor type has been proven. It's been installed on every Prius made since 2004.

The system on 2013 and up LEAFs is superior, as it includes a reversing valve so the system can run in reverse, thus becoming a heat pump. It's almost always more efficient to move heat from somewhere else than to make it from scratch. I wish Tesla would implement such a system.

 

[doctorwho]

The system on 2013 and up LEAFs is superior, as it includes a reversing valve so the system can run in reverse, thus becoming a heat pump. It's almost always more efficient to move heat from somewhere else than to make it from scratch. I wish Tesla would implement such a system.

+1 for that, a reverse cycle AC would improve winter driving efficiency

 

[smsprague]

There is too much weight put on the outside temperature. For instance, if the temp is set to 72 and it's in the 80s, it barely blows. But if it's 109 outside, it blows like a champ and cools the interior quickly. Tesla needs to tweak the software, but after two years, it still isn't a priority? Doesn't Musk ever use the climate control?

This is it!

 

[travwill]

This is it!

Agree. Now that its over 80 the A/C is doing a great job, and not having to blow that hard for long. I had issues at first when I purchased as it was in the cool 60s out and while could be hot/stuffy in cabin, it wouldn't auto cool down - had to force it. Now its doing good.

Hope they fix the algo that its using in next update or so.

 

[David99]

There is a lot more than outside vs inside temperature. How much IR radiation hits the driver makes a very significant difference what feels like a comfortable temperature. There are different sensors in most cars today (that have climate control) that try to consider it and adjust the heating and cooling. Fan speed is also not as simple as 'faster when the delta is larger'. A comfortable temperature will feel too cold if the air is moving too much. So when heating the cabin, running to fan higher will have a counter effect. That's why the Model S climate control will use the lower vents (where the legs are) when heating the car and the upper ones when cooling the car. Less airfolow in the face will make it feel warmer. More airflow in the face makes it feel cooler.

There is also no way the car can know in what state of emotion you are. If you're late and nervous, you will feel much hotter. If you're relaxed the exact same temperature will feel just fine.

I think the climate control works just fine. I always leave it in Auto and just adjust the temperature up or down depending how I feel. I really don't pay any attemtion what the number is. It's irrelevant. If I'm warm, I dial it down. If I'm cold, I'll dial it up. Don't get hung up on the numbers.

 

[jerry33]

I think the climate control works just fine. I always leave it in Auto and just adjust the temperature up or down depending how I feel. I really don't pay any attemtion what the number is. It's irrelevant. If I'm warm, I dial it down. If I'm cold, I'll dial it up. Don't get hung up on the numbers.

This is my opinion as well. If the numbers really bother you, switch to the scale you are least familiar with. If you are fluent in both, perhaps Tesla could add some of the other scales (kelvin, Rankine, or Reaumur).

 

[mattmass]

This is my opinion as well. If the numbers really bother you, switch to the scale you are least familiar with. If you are fluent in both, perhaps Tesla could add some of the other scales (kelvin, Rankine, or Reaumur).

Heh, pretty practical suggestion.

But, I think this really does point to a serious user interface issue. If you put in explicit temperature control, it should actually be capable of setting the temperature. The AC has really been the only problem I've had with he car so far.

 

[jerry33]

But, I think this really does point to a serious user interface issue. If you put in explicit temperature control, it should actually be capable of setting the temperature. The AC has really been the only problem I've had with he car so far.

All the cars with auto-climate control that I've had have worked similarly.

 

[mattmass]

All the cars with auto-climate control that I've had have worked similarly.

That sounds like the consensus. I still think it's bad UI.

 

[NOLA_Mike]

That sounds like the consensus. I still think it's bad UI.

That's certainly not my view and may not be the consensus. I can tell you that my P85D doesn't work anything like all the cars with auto-climate control that I've had (and I've had many). Like I said in my original post, my VIN 13226 worked much better than my VIN 64272 does - VIN 13226 worked similarly to all the cars with auto-climate control that I've had. VIN 13226 would go to MAX cooling if the car was hot with it set at 67 degree set point. It would stay on MAX cool for some satisfactory amount of time before starting to ramp down. I hardly had to touch it - set it at 67 and leave it. The new car will only go to MAX cool if I manually adjust it to LO.

Of course you can sweat and wait for it to cool off if you don't want to manually adjust it. My Chevrolet Silverado pickup truck with ATC has much better logic with regards to cooling (and, ergo, works much better) than my Tesla Model S P85D. I agree with you mattmass - the current logic and cooling operation in a hot, humid climate is bad.