Windows Fog Badly, best way to combat?

[ratsbew]

It's been in the 40's here recently and my windows have been fogging worse than any car I've ever owned. Normally it isn't a problem, but with the Model 3 requiring precious battery to run the heat/AC I'm trying to determine the best way to defog for the least amount of energy.

Running the HVAC at about 75º with the AC on and recirculate seems to work okay, but I hate the thought of the heat and AC fighting each other.

Should I run recirculate or fresh air? I'd think that recirculate would be more efficient since I don't have to heat outside air and so that I'm not drawing in humid outside air.

Does anyone else have tips?

BTW: I have not been using the dedicated defog button because it blasts the fan at a 7 or 8.

 

[ratsbew]

Also, does the RainX anti-fog product work well?

 

[MKandyman]

I had this issue a month or two ago when it started getting cooler outside. Switching off the recirculate function helped a lot, since it tends to bring in cool dry air versus recirculating damp air. I also only use front defrost and the floor vents.

 

[StellarRat]

The defrosters in the M3 work very well. I them for the first time last night. There might be some stuff you can spray on the windows that will help, but I don't think you'll be able to get away from using the defrost completely.

 

[Big Earl]

Clean them. Off-gassing from the interior can coat the inside of the windows and make them more susceptible to fogging.

Having the HVAC on automatic will help a lot. Having the heat and air conditioning "fight" one another is exactly how you dehumidify the air. The air conditioning cools and dehumidifies it and the heat warms it back up to a comfortable temperature for the occupants. Running the system in recirculate also exacerbates the problem, as it allows moisture from your breath, skin and clothing to build up in the car. Yes, automatic climate control uses more energy, but the result is more comfort and better visibility.

 

[ChrisH]

I just set my system to Auto and it seems to take care of everything.