Windshield defrost and AC

I really feel like a dumbass. Will somebody please exlain it to me like I'm a 5 year old with a learning disability?

When I press the windshield defrost button, it turn on to the previous temp and turns the AC on. Then I press off and the amber defrost button stays on but the AC turns off. But instead if I press the defrost button, the AC stays on along with the fan. WTF?

My wife has a 2015 Highlander and it behaves as it should.

 

AC compressor has been coming on in vehicles for the defrost cycle for well over 30 years now. Just because you don't see the AC light on means nothing, the compressor is running in defrost mode.

I will admit, I am a little confused as to exactly what the problem is that you are trying to describe. I'm sure it's the beers fault with me tonight LOL.

 

I guess I just want the off button to turn everything off, including the windshield defrost. I don't typically leave the defrost button on at all times.

 

Ok try this. From off state turn on the windshield defrost. Everything will come on, including AC and fan. Now press the defrost button again. The fan and AC stays on. Then you have to press off to turn off AC and fan that the defrost automatically turned on.

I guess I just want the defrost to turn off the AC and fan that it turned on. I live in the northwest. Windshield fog is a 9 month long issue. I don't need the AC on at all times. Fuel economy takes a hit.

Oh well, I can just live with it. All I'm asking for is a one button on and one button off for defrost.

 

The AC comes on for 2 reasons mainly. 1). The AC system dehumidifies the air (that's where the drips come from) via the evaporator coils. This quickly defrosts/dehumidifies the cabin. 2) To cycle the oil in the AC refrigerant to keep o-rings and seals in the AC system lubricated in the longer cooler months of fall and winter. You will also notice when the temp drops well below freezing the AC system will NOT come on as it could build too much pressure and damage the AC system. You will find when that happens it takes longer and in some cases you won't fully defrost/defog.

Hope this helps

 

Thanks for the info. My main concern is with the controls of #1 that you mentioned. I meant dehumidify not defrost. I guess that's a big difference.

 

By the "defrost button", do you mean the button above the fan off switch...? (Not the heated mirror button) If so, all that does is concentrate ALL of the fan's blowing power to the windshield (ie: cuts off the floor or dash vents from getting any air)..!! (look at your display that shows where the air is being directed)..Pay no attention to the A/C...!

If you hit the Fan OFF button, it kills the fan....This feature has me stumped..! Why would I want to turn OFF the fan..??

 

Yes, I meant the Defog button on top of the fan off button. When you press it, it turns on the AC and fan which is what I want it to do. Then when you press it again it leaves the AC and fan on. Then, I'll scream "Clean up after yourself you fuck!" Road rage sets in, I chase after the first fucker that cuts me off, get arrested, then my wife has to bail me out. Not an ideal situation.

 

Try this....rather than just turning the Defrost button off, can you use the heater control knob to set it to the floor/defrost setting..?? I don't know if will help you with your road rage, but hope so..

 

What are you expecting to happen when you press the button a second time? The button is meant to turn on the defrost and the fan. I see it like pressing the off button then pressing the off button again and wondering why nothing happened the second time you pressed it. Maybe I am missing your point here.

 

Thanks for that. I finally understand the logic behind the buttons. What confused me were other vehicles I've driven that has a dedicated window defog button that is self contained, as in a simple on/off that controls both fan and AC. So with Tacomas, it is like a shortcut button to quickly defog. The long way would be to change mode to windshield defog.

So the logic is, the windshield defog button is a shortcut to max out the settings to defog as quickly as possible. Then to turn off, we have to manually turn off the fan. Makes sense.

That leads me to another question, do most people leave the system on auto with AC on? I like to leave it off until needed.

 

If I need to defrost my windows I press the defrost button. It turns the fan to the high setting. When the windows are cleared off, I press the auto button.

 

So, you leave it on auto at all times? If yes, do you leave the AC on as well?

 

I leave it auto all the time unless I need to defrost the windows. If you go into the settings you can have it so the Truck doesn't turn on the AC automatically when you turn on the auto setting.
It is better to have the AC on when you are trying to defrost because it will clear the windows faster and remove moisture from the interior.

 

Yup. I know AC dehumidifies. Just baffled by the controls and the logic behind them.

Good to know that there's a setting for AC coming on automatically.

Do you know if it's set to auto with the AC on that it knows to turn on or off as needed on its own? I just don't like to unnecessarily tax my fuel economy.

 

Yes, it cycles the compressor based on the cabin temp, ambient temp, and desired temp.