Hi, I am in London (X Plaid) I was about to make an accident yesterday because of this. Never happened in any other car! this is not a user error and we do not need to have the AC on all the time! this is a fault in the system and need to be addressed.
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Windshield Defogging issues
- Thread starter ftnguyen1
- Start date
Set the Climate Control to Auto and your preferred temperature. The Climate Control system with heat pump will automatically maintain the set temperature and simultaneously remove any excess humidity from the passenger cabin. It works as designed if you let it. Turn off the Recirculate Cabin Air setting if you continue to have an issue with the windshield fogging. You can tap the front windshield defogger/defroster icon once and the front defogger/defroster will turn blue indicating that defogging has been activated. Press twice for maximum windshield defrosting.
Moisture builds up in the passenger cabin as a byproduct of the respiration of every passenger and any water/snow/ice that gets tracked into the vehicle. A full load of passengers will produce enough excess moisture through breathing that the windshield, other windows will quickly fog over in cooler/cold temperatures.
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That is a work around I will try. But honestly no other car works like that, all cars defogging system works like a charm with no need to turn it on all the time.
Internal Combustion Vehicles are constantly generating huge amounts of waste heat. Some of the warm engine coolant will flow through the cabin heat exchanger and warm the air entering the passenger cabin. Even so, you may have to run the AC a bit to defog the windshield. The heat pump in the Tesla can perform double duty. The cabin heat exchanger warms the air entering the passenger cabin while the AC evaporator coil dehumidifies the same air. It seems like these two system would be working against each other (one warming, while the other cools the air) but it works well to provide a comfortable passenger cabin without too much humidity.
“…as smart and advanced as the car is…”
If you leave the climate control in AUTO, the smart and advanced car will prevent the windshield from fogging, automatically.
fholbert
Active Member
You want to use the HVAC system to blow dry air, warm/hot air seems to work almost immediately for me.
Been like that for me since I bought a new 1977 Monte Carlo.
Came here because we're having a similar problem with our Model S. Driving on a rainy night with system on "Auto" mode and window started fogging up. Turned defogger on, both defrost, and defog mode, and didn't have real effect until manually turning the fan to "11". Left it in that mode, and ~20 minutes later the window suddenly and dangerously fogged up entirely, blocking vision. Cycled defogger to defrost, off, and then back to defog, turned fan back to 11, and window cleared. However, ~20 minutes later, same thing happened again - and this has repeated at least 4 times!
Keep in mind that the window is suddenly fogging with the defogger having been on for a while on '11'!
What could cause this? We had the window repaired recently. Could this be a flaw in how it was installed?
Keep in mind that the window is suddenly fogging with the defogger having been on for a while on '11'!
What could cause this? We had the window repaired recently. Could this be a flaw in how it was installed?
It sounds like you have a problem with your HVAC system. Perhaps the compressor isn't working correctly, causing the system to be able to dehumidify.
Did you have Recirculate Cabin Air turned on? If the passenger cabin is fully loaded and everyone has wet shoes, umbrellas, etc. the relative humidity level inside the vehicle can quickly become 100%. Turn off Circulate Cabin Air if this happens again.
Brian-MS90D
Member
You could have an issue with your window as your surmised.
Also, depending on the age of your Model S, some of them had a known a problem where the internal vent diverter actuator would get stuck because the track the arm moved in would grind a groove that would inhibit further motion. If you hear the fan blowing hard, but little is happening (not cooling, not heating, low air flow coming out of the vents), then you could have a failed actuator that needs to be replaced.
The problem was using "Auto" mode. At our service appointment, they told us in that situation to take it off Auto and not use the window defogging button, but simply manually select the window air, turn on AC, and turn the fans to 11....
I think the problem is that when we used the window defogging button (in 'blue' mode), though it turned on the AC and directed the air, it also turned down the fan, so it couldn't handle the environment. And then when we manually turned the fan up, it took it off auto, and probably redirected the air so that it wasn't blowing on the window....
I think the problem is that when we used the window defogging button (in 'blue' mode), though it turned on the AC and directed the air, it also turned down the fan, so it couldn't handle the environment. And then when we manually turned the fan up, it took it off auto, and probably redirected the air so that it wasn't blowing on the window....
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