[tmiller0399]

When having the climate control set to auto shouldn't the front windshield defrost activate automatically ? I was driving this morning in light drizzle that started to freeze on my windshield. The system never changed to blow air on the now semi obstructed windshield and I had to change it to manual. Then when I left work I auto started the van and it automatically turned on the rear defrost but again did not turn on front defrost. If this is how it is supposed to react it is very very stupid. does anyone else have experience with this in cold freezing weather ? Kind of defeats the "auto" setting.

 

[generaltso]

The Auto setting will automatically control the temperature and fan speed, but not where the air comes out. I don't think there are any sensors to know if there is frost on the lower windshield. If you remote start in the cold, the front defrost will be on, but only until you get in and hit the start button.

When you need air on the windshield, hit the front defrost button. When it's done defrosting, hit the Auto button to put it back in Auto mode.

 

[tmiller0399]

If that is true, why was the rear defrost on when I auto started the car ? SO in auto air only comes out of the bottom vents by your feet ? That is where mine always seem to blow and no where else in auto.

 

[generaltso]

If that is true, why was the rear defrost on when I auto started the car ? SO in auto air only comes out of the bottom vents by your feet ? That is where mine always seem to blow and no where else in auto.

The rear defrost also comes on when you remote start the car in the cold, but that stays on after hitting the start button, unlike the front defrost. I assume Chrysler designed it this way intentionally. They probably figured that people would want the heat directed at them when they get in the car instead of the windshield.

Do auto climate systems in other cars automatically send air to the windshield when it's got frost on it?

 

[tmiller0399]

My last vehicle was a 2015 Nissan Murano and I never remember having to take that off of auto so I can only assume it directed it to the windshield. It definitely switched between the floor and dash vents or did both, I cannot remember for sure. I do not like the fact that any manual control I do with the heater on the van drops it from auto. I would think I cold change which vents the air came out of and still have it control fan and temp. I do not think this is the case and once I make any change it goes into a full manual mode. Or maybe I'm wrong ??

 

[generaltso]

Not sure. I only ever switch between auto and front defrost. I never change any of the manual settings.

 

[generaltso]

Okay, so I paid more attention to what the HVAC was doing on my way to work this morning while set to Auto. I started the car normally and drove away. There was no air coming out anywhere for the first few minutes while the car was warming up. Once the car warmed up, the fan started blowing hot air at the windshield at a fairly fast fan speed. After about 5 minutes of this, it switched to mostly coming out by the floor and the fan speed was reduced.

So I guess my earlier statement was incorrect. The Auto setting DOES seem to automatically change where the air comes out. But I still don't think it's sensing any frost on the windshield. It's just blowing at the windshield for a few minutes to make sure.

By the way, this only applies to cold weather operation. When it's hot out, the A/C automatically turns on and the air comes out the front vents.

 

[mtmgtz]

There aren't any vehicles out there that sense frost on the windshield. The vehicle just knows the outside temp and if you remote start it in cold temps, it will likely defrost everything that could be frosted up while sitting parked. It isn't going to know if you windshield frosts up while driving.

I haven't messed with anything but the temperature adjustments on ours. Been on Auto the entire time and haven't had any issues.

 

[generaltso]

The vehicle just knows the outside temp and if you remote start it in cold temps, it will likely defrost everything that could be frosted up while sitting parked.

Right, it definitely does this when you do a remote start. But I started the car manually this morning, and after driving for a couple of minutes, the air started blowing at the windshield. I never really paid attention before, but it apparently does this when it's cold outside. If the windshield were to start frosting after it switches to the floor vents, you'd have to manually hit the front defrost button, which I've done but not very often.

 

[mtmgtz]

Right, it definitely does this when you do a remote start. But I started the car manually this morning, and after driving for a couple of minutes, the air started blowing at the windshield. I never really paid attention before, but it apparently does this when it's cold outside. If the windshield were to start frosting after it switches to the floor vents, you'd have to manually hit the front defrost button, which I've done but not very often.

Yea, I haven't paid much attention to the defrost air flow on cold starts. I don't like defrost on unless I need it as my eyes dry out really bad with it on above low. I have contacts so that doesn't help.