Range mode in cold weather caused ice build up on windshield

[Zoomdude]

I was driving (MS201875d) at about 80 km/h (50 mph) at -14°C (7°F) with heavy snow. Range mode turned on as recommended by the owners manual for best practise in cold weather. Car was preheated for 45 minutes before departure. After about 30 minutes ice started building up on the windshield so I turned on manual heating for the windshield which resulted in fog build up on all windows. I whent from bad to zero visibility in 5 seconds on a highway. That was scary with kids in car.

Tesla service tells me this is normal behaviour. Is it? My take is that I used the car as intended and then found myself in a very serious situation.
They also state that the recommendation for using range mode is not present in the manual, but it is - Cold Weather Best Practices/While Driving Model S Owner's Manual | Tesla

I feel like this issue should be handled more serious, but I like a second opinion on this.

 

[mswlogo]

Did you hit the windshield defrost button TWICE so it’s HEATED - DRY air.

Works every time and my car is always in range mode.

Occasionally when it first comes on it might fog up instantsly then immediately starts to clear.

Once click on defrost works most of the time or to maintain. But it’s slower. Heated dry air works the fastest.

Also if things are bad you sometimes can’t use recirculate.

 

[KalJoMoS]

Did you had the HVAC on auto?

 

[serendipitous]

Range mode's whole purpose is to reduce HVAC system power consumption by disabling/significantly reducing AC and resistive battery/cabin heating to give you longer range. The manual doesn't recommend it generically - it recommends it under the section: "Follow these suggestions to reduce energy consumption" - when you are willing and able to sacrifice comfort. Obviously in damp cold conditions it's not safe to do that - you need dry warm air.

 

[Zoomdude]

Did you had the HVAC on auto?

Yes

 

[Zoomdude]

Range mode's whole purpose is to reduce HVAC system power consumption by disabling/significantly reducing AC and resistive battery/cabin heating to give you longer range. The manual doesn't recommend it generically - it recommends it under the section: "Follow these suggestions to reduce energy consumption" - when you are willing and able to sacrifice comfort. Obviously in damp cold conditions it's not safe to do that - you need dry warm air.

Well if you read under the section "Cold Weather Best Practices" in the owners manual it states that:"Turn on Range Mode (if equipped) to automatically limit the power that the climate control system uses to maintain the temperature of the Battery and the cabin area."

Is it really obvious that ice will build up on the windshield if it snows?

 

[KalJoMoS]

Yes

I have noticed that Auto mode on HVAC and Range Mode does not work well together. You had quite dramatic situation but if you change the HVAC to Manual, it will not get that fogged. Of course you need to set the speed and airflow selections on your own. I have not used Auto mode ever since.

 

[ucmndd]

Since you’re reading the manual - check the part about how to use the defroster. Press it twice, so the icon turns red, for actual hot air defrosting (vs. de-fogging).