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Pre-warming the Cabin: What'd I do wrong?!

It was well below freezing this morning, and the app showed my garaged MS had an interior temperature of 50F. Thought it would be nice to be warmer when I left for an early appointment, so I turned on climate, setting it for 65 -- a 15-degree increase would be plenty.

Yet when I got to the garage a half-hour later, I found the air conditioning running full blast, working like heck to get the temperature DOWN. Seriously? Dead of winter, with the set driver profile having the AC off, and it turns it on? I wanted it warm, not a meat locker.

So what the heck did I do wrong, to keep this from happening again?
 

Nitemare3219

Member
Aug 25, 2017
119
112
Ohio
Just because it says A/C on doesn't mean it's trying to cool the cabin off. What was the temperature reading in the app after you got in the car - did you check? A/C on is used even when it's freezing outside to reduce humidity & fogging. It can still warm the air even with the A/C running. Try a higher temperature next time... 68 is a pretty good number for me.
 
I live in Colorado: what's this "humidity" you all are speaking of?

Yes, AC was on: it was very cold. No, I didn't delay my trip to connect to my phone to see what the temp was down to.

The thought remains that when you set a target temp significantly higher than the current temp, it should turn on the heat, not the AC. So I guess the bottom line reply to my question is, I didn't do anything wrong, Tesla programmers did.
 

PrGrPa

Member
Aug 12, 2017
331
164
Manchester
Maybe Colorado has no moisture in the air. Here in the north of England turning on the heater in winter without also running the air conditioning produces a wonderfully fogged windscreen. Given the modest extra energy needed to run air conditioning and heat over heat alone it seems reasonable to run it. Though I can see how peculiar it must seem to you.
 

BrettS

Active Member
Mar 28, 2017
2,155
2,570
Orlando, FL
I live in Colorado: what's this "humidity" you all are speaking of?

Yes, AC was on: it was very cold. No, I didn't delay my trip to connect to my phone to see what the temp was down to.

The thought remains that when you set a target temp significantly higher than the current temp, it should turn on the heat, not the AC. So I guess the bottom line reply to my question is, I didn't do anything wrong, Tesla programmers did.

There may be a little confusion in what different people mean by “AC”. As some people mentioned earlier, it is normal for the AC compressor to run while the heater is on in the car. The air coming out will be warm, but the AC compressor will be running to dehumidify the air. If you look at the status on the display you will see where it says that the AC is on. But when you said the AC was on I think what you meant is that you felt cold air coming out of the vents. This would not be normal if the car was trying to heat the cabin. However, I’m not sure it was trying to heat the cabin at that point.

Once the car reaches the temperature you set (and it can do so fairly quickly since it’s a small space) then it will maintain that temperature. 65 degrees is still a fairly cool temperature and while the heater might have run for a short time to bring the cabin up to 65 from 50 degrees, once it reached 65 then the air coming out of the vents would be about 65 degrees so it can maintain the temperature that you asked it to. Particularly if the fan wasn’t set on auto, but manually set at a high level, 65 degree air coming out of the vents could definitely feel like the air conditioner blasting.

What did you do when you got into the car to drive off? Did you turn the temp up or did you leave it set to 65? I’m assuming you turned it up higher than 65, which would cause it to run the heater again to warm up the car more. Next time you preheat the cabin you should set it to whatever temperature you want the cabin to be at as you drive. Also check to make sure that the fan is in ‘auto’ mode. Once the set temperature is reached then it will turn the fan speed down very low, so even if there is cooler air coming out of the vents it won’t blast you.
 

SR-75

Member
Nov 19, 2016
173
172
Lincoln, CA
Did you check to see if the fan was set to a number or auto?

I find that sometimes I accidentally move the right side wheel which takes the fan off of auto and set to about "5" and the fan just stays on at that level until you lower it or put it back on auto.
 

Xenoilphobe

Active Member
Jan 2, 2014
4,620
4,546
Fairfax County, Virginia
I always hit Max heat, for both the wife's and my car.. only challenge is she leaves about 30 minutes before me and one morning while she was driving I cranked the heat in her car verses mine....

That night she came home all worried, and said she had her "big day" had arrived, I looked at her and she explained that she was going through menopause and that she was burning up this morning in the car with hot flashes, I then realized what I had done.... :(

I finally told her a couple weeks later when she did it to me!!... the damn Apple Watch App is a bit confusing with two S's.

Now if they could just get the steering wheel to heat too from the App...
 

BrettS

Active Member
Mar 28, 2017
2,155
2,570
Orlando, FL
one morning while she was driving I cranked the heat in her car verses mine....

My aunt and uncle have an electric blanket with separate settings for each side and two controls. One time after my aunt washed the bedding she accidentally reversed the controls on the electric blanket as she remade the bed. That night my uncle was warm, so he kept turning down his control and my aunt was cold, so she kept turning hers up and it took them several hours before they realized what was happening.
 
What did you do when you got into the car to drive off? Did you turn the temp up or did you leave it set to 65?

Normally, I'd leave it at 65 -- that's plenty warm for conditions here (not much snow lately), especially with seat heaters, so that's why I set it there in the first place. But in this case, since it was so frigging cold having the AC on in the winter, I turned it up to get the chill reversed, then dropped it back to 65 about 15 minutes later.

No need to check the phone, but what did the car indicate as the set temperature when you got in?

65, as I had set it. The interior was nowhere near that warm, and the vents were blowing very cold air at a high fan setting.

Did you check to see if the fan was set to a number or auto?

Auto -- which I think is what always gets set when I use cabin pre-warm/cool.
 
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