Remote Start and Front Defroster

corneileous · Jan 15, 2021

BulaienS said:
This is the answer I was looking for. The key is the engine has to be at operating temperature before the front defroster blower really kicks in and blows hard. Thank you Ricks Ram, Corneileous and Ramagain!

Glad we could help.

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corneileous · Jan 18, 2021

Just came out to my truck this frosty morning where Weatherbug says 30° but the temp sensor on the truck says 25.... remote started, came out almost the full ten minutes later and when I opened the door, system was in auto, and the defrost had pretty much the entire windshield cleared off.

Y’all just got a let it idle for longer than three minutes and make sure everything‘s in auto…

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BulaienS · Jan 21, 2021

corneileous said:
Just came out to my truck this frosty morning where Weatherbug says 30° but the temp sensor on the truck says 25.... remote started, came out almost the full ten minutes later and when I opened the door, system was in auto, and the defrost had pretty much the entire windshield cleared off.

Y’all just got a let it idle for longer than three minutes and make sure everything‘s in auto…

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BulaienS · Jan 21, 2021

UPDATE: My previous replies indicated that I agreed with Ricks Ram and Corneileoous, but I have to take those back. Yes, I agree that the front window did partially clear but you have to let the truck completely warm up. The warm air inside the cabin will eventually clear your windshield, but that was not why I created this discussion. I just tested this twice this week by letting the truck warm up by using remote start and leaving the heating system in Auto. 10 minutes later I entered the vehicle and found the front defroster was not blowing. Yes, the window was partially cleared but not because the front defroster was blowing. If the front defroster was working, I feel, the windshield would clear sooner and better even when the engine temp has not reached operating temperature and you would not need to wait so long to have the benefit of a cleared windshield. So, my concern still stands that the Auto heating system design should be that the front defroster would be blowing when the temp is 40F or below, instead of having to select the front defroster before turning off your engine so that it will be blowing the next time you use remote start.

ToyHaulin · Jan 21, 2021

Ricks Ram said:
the system won't start to blow hard until the engine reaches a certain temperature so it's not just blowing cold air.

I can't appreciate that. On my Honda, the auto climate control always ran the front defrost when you first started the vehicle. It blew lightly when the vehicle was cold and increased as the it warmed and then vented the front windows less as time went on.

On my Buick, remote start put the blower on high until you unlocked the doors.

I remember reading the Jeep Grand Cherokee had infrared sensors to measure the driver's skin temperature so the climate control could adjust for that too.

Maybe Dodge isn't putting much effort into this.

corneileous · Jan 21, 2021

BulaienS said:
UPDATE: My previous replies indicated that I agreed with Ricks Ram and Corneileoous, but I have to take those back. Yes, I agree that the front window did partially clear but you have to let the truck completely warm up. The warm air inside the cabin will eventually clear your windshield, but that was not why I created this discussion. I just tested this twice this week by letting the truck warm up by using remote start and leaving the heating system in Auto. 10 minutes later I entered the vehicle and found the front defroster was not blowing. Yes, the window was partially cleared but not because the front defroster was blowing. If the front defroster was working, I feel, the windshield would clear sooner and better even when the engine temp has not reached operating temperature and you would not need to wait so long to have the benefit of a cleared windshield. So, my concern still stands that the Auto heating system design should be that the front defroster would be blowing when the temp is 40F or below, instead of having to select the front defroster before turning off your engine so that it will be blowing the next time you use remote start.

If it’s just 40°, it probably won’t turn your defrost on if we’re just talking about a fogged up window. Like I told you before, the only time really where my defrost would actually turn on automatically was if the windshield was actually frosted over or if the outside temperature was actually a lot closer to freezing.

I couldn’t find it in the manual anywhere where it talks about it but I’m pretty sure there’s nothing wrong with your system because if you remote start it and when you go to leave, if your window is fogged over, I believe it’s just up to you the driver to push the defrost button and crank the fan speed to maximum to defog your window. I’ll betcha this is normal operation.

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chri5k · Jan 22, 2021

I leave my system on Auto all the time but have the opposite problem. The system turns on the defroster when their is no frost and won't blow warm air on my feet. I have to take it out of Auto and manually select feet. I have the CTD and plug in the engine heater on cold nights.

After everything warms up, I can put it back on Auto and it sends warm air to feet and face as normal.

corneileous · Jan 22, 2021

OP, I just got in my truck this morning to head to work. Had a slight fogging on the inside of the windshield when I got in it. Outside temperature according to the sensor in the mirror bounces between 41° and 43°. My defrost wasn’t on, it was only out the floor vents but either there was just enough rising heat that it defogged most of the windshield or maybe the truck was alternating the air flow between floor and defrost, I don’t know. I just know that the air wasn’t full-blown shooting from the upper dash vents

As I said, I think your system may just be running how it’s supposed to.

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corneileous · Jan 22, 2021

chri5k said:
I leave my system on Auto all the time but have the opposite problem. The system turns on the defroster when their is no frost and won't blow warm air on my feet. I have to take it out of Auto and manually select feet. I have the CTD and plug in the engine heater on cold nights.

After everything warms up, I can put it back on Auto and it sends warm air to feet and face as normal.

How old is this truck? In your case, yours sounds like a messed up humidity sensor.

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chri5k · Jan 22, 2021

corneileous said:
How old is this truck? In your case, yours sounds like a messed up humidity sensor.

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It is a 2016 2500 so no humidity sensor.

corneileous · Jan 22, 2021

chri5k said:
It is a 2016 2500 so no humidity sensor.

You sure? Says right here there should be one that’s for a 2012 to a 2020. Do you have that little square box looking thing with a wiring harness that goes to it that’s stuck to the top of your windshield? If so, that’s your humidity sensor. If you have automatic temperature control on your HVAC, you should have a humidity sensor.

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chri5k · Jan 22, 2021

100% sure. 2500 and up do not have humidity sensors.

corneileous · Jan 22, 2021

chri5k said:
100% sure. 2500 and up do not have humidity sensors.

Hmm. Well, that’s dumb. I wonder why they don’t. But then again, I’m still wondering why since the 2500s and up use the same exact tow mirrors that they put on the 1500’s but they won’t let the those mirrors fold in electrically like they do on the heavy duty‘s.

But anyways, I guess you got your problem solved. Without that humidity sensor, you’re probably gonna have to just only leave your auto button pressed in at night when the weather forecast says the low should be close to freezing and on the mornings when it’s not supposed to be as cold, I would turn the auto function off when you park at night if you don’t want the defrost to be on all the time when it’s not needed.

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BulaienS · Jan 22, 2021

corneileous said:
If it’s just 40°, it probably won’t turn your defrost on if we’re just talking about a fogged up window. Like I told you before, the only time really where my defrost would actually turn on automatically was if the windshield was actually frosted over or if the outside temperature was actually a lot closer to freezing.

I couldn’t find it in the manual anywhere where it talks about it but I’m pretty sure there’s nothing wrong with your system because if you remote start it and when you go to leave, if your window is fogged over, I believe it’s just up to you the driver to push the defrost button and crank the fan speed to maximum to defog your window. I’ll betcha this is normal operation.

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It was between 19 and 23 degrees both days during these test sessions here in Wisconsin. I'm not saying the system is broken, only that it does not have the proper programming for the Auto heating system.

corneileous · Jan 22, 2021

BulaienS said:
It was between 19 and 23 degrees both days during these test sessions here in Wisconsin. I'm not saying the system is broken, only that it does not have the proper programming for the Auto heating system.

So even when it was that cold, was your windshield iced over to the point you couldn’t see out of it? Has there ever been a time where you’ve remote started your truck and the thing was actually in defrost mode while in auto? If it never has, I’d say your humidity sensor is bad or maybe they can calibrate it.

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BulaienS · Jan 25, 2021

Yes, the exterior of my windshield was iced over and the defrost blower was not blowing, and the defrost button was not lit. The frost is on the outside not inside, so I don't think the humidity sensor is applicable since that is sensing the interior.

corneileous · Jan 25, 2021

BulaienS said:
Yes, the exterior of my windshield was iced over and the defrost blower was not blowing, and the defrost button was not lit. The frost is on the outside not inside, so I don't think the humidity sensor is applicable since that is sensing the interior.

Have you consulted with the dealer because, to be honest with you, I’m really not sure how the truck “determines” when to automatically direct the air flow up though your top defroster vents on the dash. Maybe it isn’t the humidity sensor- that might actually only be for like when you’re driving somewhere with the heater on and your windows start to fog up, the humidity sensor senses that and turns the defrost on for you, I don’t know.

All I can say at this point is either give the dealer a call and ask them or on those cold nights, you might just have to treat it like it’s not an auto-Hvac and when you park the night before, just manually put your system in defrost on high heat with the fan turned to its highest setting. That’s all I know at this point.

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BulaienS · Jan 26, 2021

That's what the last sentence of my beginning statement for this thread states, that I did contact the dealer and they contacted Chrysler, their response was only in regard to interior conditions. You are right that I have to continue to do what I have been doing. Turning on the defroster blower before turning off the engine. Still, there is no reason why the front defroster would always blow when the temp is 40 or below and not need to know what the frost or snow conditions are. The truck will heat up to the proper temp just as it would for when the blower is not going. At least the interior AND exterior window would be cleared, whether it needed or not. Maybe the 2021 or 2022 model will be updated.

corneileous · Jan 26, 2021

Well either there’s something a whole lot different between yours and mine or something just ain’t working right. Just came out to my truck this morning- radio screen says it’s 28°, was no frost on the windshield but even after about probably five minutes of idling, I noticed that the defroster was on this morning so, I wish I could be more help.

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BulaienS · Jan 26, 2021

Maybe the difference is between the 2018 and 2020 model years.

Remote Start and Front Defroster

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