# Heater and AC inconsistencies



## harrison987

Hey everyone...

Can someone please explain the inconsistent temperatures with the heating and A/C?

When I had my Mercedes...when I had the cabin temp set to 74 degree...it was a constant. No matter what the temperature was OUTSIDE...the cabin was a perfect 74 degrees. They say 72 is the best setting, but I found it waaaaaaaaaaaay too cold. 74 was perfect.

With my M3, there is really no consistency...and it appears outside temperature plays a part (?)

When I have it set at 74...for sure it is not the same "74" I had in my Mercedes. Sometimes it is really cold...other times...it is really warm. I find myself constantly having to re-adjust quite a few degrees up or down to get to the right temp. ON a hot day in LA, I remember driving in 95 degree weather, and having to turn it down to MAX cooling just to be comfortable...but that eventually turned out warm air as well (no cool air)...

I assume this has to do with the fact that the system is not working off engine heat or AC compressor?


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## jmaddr

I don’t have any issue and keep it nailed at 74 but I do have tint. Do/did you have the same level of tint on both cars?

It would be interesting to know where the interior temperature sensor is on both cars. With all the glass in a TM3, I could see it getting hotter faster close to the roof of the car.


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## Ed Woodrick

The one thing that I can say for sure, is that 74 doesn't always feel like 74. Humidity plays a big part of it as well as ambient temperatures. That's why you hear the weathercasters talk about "feel like" temperatures.

What you are possibly feeling is a difference in airflow in the car and the ambient temperatures. Also, even in your other car, I can guarantee you that it was never the same temperature in all parts of the passenger compartment, probably varied more then 10 degrees.

I remember a number of years ago I walked into a large data center, one of those places that highly regulate both humidity and temperature to something like 68 degrees, well, it was HOT inside. It was really hot, but no one was freaking out. Then I remembered that I had been outside in 30 degree temperatures for awhile.

My experience with a Model 3 and a Model Y is that there are times where a 1 or 2 degree change in the set temperature is warranted. Change it, give it a few minutes and things usually come back to a good temperature. (Changing it more than 2 degrees just puts it out of whack)


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## kpedraja

harrison987 said:


> Hey everyone...
> 
> Can someone please explain the inconsistent temperatures with the heating and A/C?
> 
> When I had my Mercedes...when I had the cabin temp set to 74 degree...it was a constant. No matter what the temperature was OUTSIDE...the cabin was a perfect 74 degrees. They say 72 is the best setting, but I found it waaaaaaaaaaaay too cold. 74 was perfect.
> 
> With my M3, there is really no consistency...and it appears outside temperature plays a part (?)
> 
> When I have it set at 74...for sure it is not the same "74" I had in my Mercedes. Sometimes it is really cold...other times...it is really warm. I find myself constantly having to re-adjust quite a few degrees up or down to get to the right temp. ON a hot day in LA, I remember driving in 95 degree weather, and having to turn it down to MAX cooling just to be comfortable...but that eventually turned out warm air as well (no cool air)...
> 
> I assume this has to do with the fact that the system is not working off engine heat or AC compressor?


Ya. I've just found inconsistent AC/heater performance all around with the Model 3. We've experienced it first hand on recent trips where the AC couldn't keep up even with moderate temperatures (75-80º) with little to no airflow no matter what we set the temp to. Other times it blasts cold air when it's really hot out without any problems. My 18 year old BMW wagon had better AC performance.

One thing I've started to do consistently when using the AC on hotter days is make sure the recirculation is turned on. It seems to turn itself off by default. But with recirc on I seem to get a more consistent temperature.


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## Garlan Garner

harrison987 said:


> Hey everyone...
> 
> Can someone please explain the inconsistent temperatures with the heating and A/C?
> 
> When I had my Mercedes...when I had the cabin temp set to 74 degree...it was a constant. No matter what the temperature was OUTSIDE...the cabin was a perfect 74 degrees. They say 72 is the best setting, but I found it waaaaaaaaaaaay too cold. 74 was perfect.
> 
> With my M3, there is really no consistency...and it appears outside temperature plays a part (?)
> 
> When I have it set at 74...for sure it is not the same "74" I had in my Mercedes. Sometimes it is really cold...other times...it is really warm. I find myself constantly having to re-adjust quite a few degrees up or down to get to the right temp. ON a hot day in LA, I remember driving in 95 degree weather, and having to turn it down to MAX cooling just to be comfortable...but that eventually turned out warm air as well (no cool air)...
> 
> I assume this has to do with the fact that the system is not working off engine heat or AC compressor?


The thermostat sensor is behind the screen - on the bottom of the plastic arm that holds the screen to the car.

NOW.....I used to experience what you are talking about, however I no longer have the inconsistent temperatures. Why? Because....I ordered the Swivel Screen kit online from that wonderful guy in the Chicagoland area.
The Swivel Screen Mount kit causes you to remove the plastic bottom piece of the arm that holds the screen to the car permanently and mount the sensor on a rigid fabric replacement covering.

I believe the fabric maintains a much more static temperature than the plastic piece that came with the car. That is my theory.

Lastly....that screen gets pretty warm when lit and heats up that arm that has the thermostat sensor mounted on it. Hmmmm However, the screen doesn't heat up my new fabric ( or the air surrounding it ) nearly as much. Hmmmmm

Watch this video from Minute 27 to the end.
TESLA Model 3 Adjustable Screen Mount Kit from Tech Forum & RPM TESLA - Bing video

Tesla Model 3 adjustable screen mount kit update and sale! - Bing video


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## Madmolecule

Garlan Garner said:


> The thermostat sensor is behind the screen - on the bottom of the plastic arm that holds the screen to the car.
> 
> NOW.....I used to experience what you are talking about, however I no longer have the inconsistent temperatures. Why? Because....I ordered the Swivel Screen kit online from that wonderful guy in the Chicagoland area.
> The Swivel Screen Mount kit causes you to remove the plastic bottom piece of the arm that holds the screen to the car permanently and mount the sensor on a rigid fabric replacement covering.
> 
> I believe the fabric maintains a much more static temperature than the plastic piece that came with the car. That is my theory.
> 
> Lastly....that screen gets pretty warm when lit and heats up that arm that has the thermostat sensor mounted on it. Hmmmm However, the screen doesn't heat up my new fabric ( or the air surrounding it ) nearly as much. Hmmmmm
> 
> Watch this video from Minute 27 to the end.
> TESLA Model 3 Adjustable Screen Mount Kit from Tech Forum & RPM TESLA - Bing video
> 
> Tesla Model 3 adjustable screen mount kit update and sale! - Bing video


Just added the screen swivel. I was suprised at the cabin temperature sensor mounting location. It does seem like it could be influenced by screen temperature but also it has very poor circulation where it is, and just seems like an odd placement. You could move the temperature sensor without having to go with the screen swivel. I really enjoy the new screen angle and actually like it being a little bit lower also.

I did go with a different model to save a couple bucks and it could be shipped a little quicker. I do wish I would've bought it from the Chicago guy. He does seem like a really nice guy and very helpful in the videos. One note I noticed in watching the two videos is he only puts the screen in clean mode when he removes it. The video I watch for the one I purchased had you power off the screen and do all the Modifications from the passenger seat and don't open the driver door to leave it powered off. I don't know if it makes any difference but it seemed a little safer approach.


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