IS - 3rd Gen (2014-present) Discussion about the 2014+ model IS models

Windshield defog function

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Old Oct 5, 2021 | 10:58 AM
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Default Windshield defog function

Hope everyone is doing well. Have a question regarding the windshield defog function as we are getting more and more rainy days.

With the climate controls set to manual, a/c set to off and fan direction set to windshield and feet, the air coming out from the vents is cold. Cold as if the A/C is on. This makes the cabin uncomfortably cold even with the temperature set to 20C.

I would prefer to keep the fan direction set at the windshield/feet rather than keep switching it since this keeps the windshield clear during the whole drive.

Any tips for how to keep the windshield defogged and clear, while maintaining a comfortable cabin temperature?
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Old Oct 5, 2021 | 12:36 PM
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When you set the vents to windshield or windshield/foot, the AC is running, that's why it feels cold.
In those positions the AC button does not need to be on, and will not light up, but the AC compressor is running for sure.

If you want to leave it in that position, then simply increase the temp to something that is more comfortable for you, like 22C...really it's your preference.

The AC simply removes moisture from the air, which defogs the windshield/windows...the temperature of the are coming out the vents is still to your discretion.
The AC will remove the moisture regardless if you have the temp set to max cold or max hot.
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Old Oct 5, 2021 | 01:38 PM
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Originally Posted by srv777
Hope everyone is doing well. Have a question regarding the windshield defog function as we are getting more and more rainy days.

With the climate controls set to manual, a/c set to off and fan direction set to windshield and feet, the air coming out from the vents is cold. Cold as if the A/C is on. This makes the cabin uncomfortably cold even with the temperature set to 20C.

I would prefer to keep the fan direction set at the windshield/feet rather than keep switching it since this keeps the windshield clear during the whole drive.

Any tips for how to keep the windshield defogged and clear, while maintaining a comfortable cabin temperature?
AC on will help. The air conditioner has nothing to do with temperature. Leave it on.
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Old Oct 5, 2021 | 02:59 PM
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My preference is to have the vents pointed to the windshield, but not have the A/C on. Does not sound like this is an option for our cars. Still remember doing a hack on Honda's way back to disable the A/C for exactly this reason.

Trying to save the few extra MPG without A/C running as gas prices are getting outrageous here
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Old Oct 5, 2021 | 06:48 PM
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Originally Posted by srv777
Trying to save the few extra MPG without A/C running as gas prices are getting outrageous here
This is not answering your defog question, but if you are turning the AC off and rolling down windows instead, you may be getting lower gas mileage from drag than you would with AC running and windows up.
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Old Oct 5, 2021 | 07:54 PM
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Originally Posted by srv777
My preference is to have the vents pointed to the windshield, but not have the A/C on. Does not sound like this is an option for our cars. Still remember doing a hack on Honda's way back to disable the A/C for exactly this reason.

Trying to save the few extra MPG without A/C running as gas prices are getting outrageous here
I’m not sure how blowing moist air at a fogged window will help. The Air compressor dries out the air in order to defog the window.

And I’m sure the compressor running isn’t killing your mpg by that much. I understand gas is up but I’m sure there’s better ways to save $4.
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Old Oct 9, 2021 | 12:17 PM
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When you put the windshield defrost on, it switches to using outside air and doesn't change to cabin only air, but when you use the defroster + foot option, you can turn AC off + cabin air only. I know in the thread it was mentioned that the A/C is still running, does that mean it's still using air from the outside as well? I hate the smell of outside cars when I drive
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Old Oct 9, 2021 | 06:20 PM
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Originally Posted by swaangin
When you put the windshield defrost on, it switches to using outside air and doesn't change to cabin only air, but when you use the defroster + foot option, you can turn AC off + cabin air only. I know in the thread it was mentioned that the A/C is still running, does that mean it's still using air from the outside as well? I hate the smell of outside cars when I drive
When the HVAC controls is set to Defrost or Foot+Defrost the AC is running regardless if the AC button light is lit or not...this is a default operation programmed into the AC Amplifier.
You can however switch between Fresh Air or Recirc as you desire...the lights for the button will illuminate depending on what you select.
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Old Oct 9, 2021 | 06:37 PM
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Originally Posted by Sasnuke
When the HVAC controls is set to Defrost or Foot+Defrost the AC is running regardless if the AC button light is lit or not...this is a default operation programmed into the AC Amplifier.
You can however switch between Fresh Air or Recirc as you desire...the lights for the button will illuminate depending on what you select.
Thanks for clearing that up. However, (not sure if this is with everyone's car) when I have de-frost (only), it doesn't let me change to Recirc. The light doesn't light up no matter how much I press it, however, defrost + foot = recirc is available so I wasn't sure why that was the case
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Old Oct 9, 2021 | 06:49 PM
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Originally Posted by swaangin
Thanks for clearing that up. However, (not sure if this is with everyone's car) when I have de-frost (only), it doesn't let me change to Recirc. The light doesn't light up no matter how much I press it, however, defrost + foot = recirc is available so I wasn't sure why that was the case
I'm going to have to try that on my own car tomorrow. Honestly I use defrost very rarely, an obviously only in winter...which looks like it's going to be brutal this year.
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