when it is well below freezing and driving in snow storm or freezing rain, my defroster is having difficulty keeping up. Window ices.
The heat is hot, and the auto temp switch seems to be directing the air to panel/defrost/floor properly when switched, so I dont think it is the blender door, although the defroster never did have extreme pressure at the best of times when new.
Is it possible there is a hose off or loose for just the defrost position and can it be checked without pulling the whole dash apart?

I'm just out of warranty and would rather not spend a mint on this at the dealership cause its only a pain when driving on the worst of winter days.

Maybe a winter front would help, or a higher thermostat for winter, but then again when I drive it to Florida in Feb., wouldnt want it to boil over on the I-95!
Any thoughts on how to improve defrosting in extreme cold appreciated.

 

All i ever do when the heater isnt enough is just switch it to just defrost, with fresh air and the a/c on but i have the normal climate control, and have zero issues with freezing up or fogging even last night when it was -25 C

where does your truck run on the temp gauge? mine is just over half and thats 192f on the edge it gets nice and hot in the cab

 

Leaving the Auto A/C on Auto won't work in your case. I ran into that while driving through the Rocky Mtns. I had to put it on Defrost only.

The Auto mode sends air everywhere...did you know you have air ducts under your seat, and in the center console(if installed)...and they are getting air almost always?

That's why it's necessary to put it on Defrost only. This forces most of the hot air at the windshield and side windows.

Once I figured it out, I was driving in 0-20F conditions without any problems with frost or snow in my viewing area...the side pillar piled up of course though

 

the temp gauge is straight up and down when fully warmed and the heat is pretty hot, but even in the full defrost position, most of the air comes out in the middle behind the radio area, and the window ices opposite the driver's left eye...most annoying.
Shouldnt the pressure be the same in all 3 defrost vents, not just strong in the middle?

 

My 2005 has the same problem so what I did was partially cover the holes that send air to the side windows which forced more air to the windshield.

 

close your heater vents cause i noticed on my 06 that even on defrost some air still blows out the pannel vents.... might help you its been -30 to -45c hear for the last week and my windows dont frost up. maybe its too dam cold to freez lol... al i know is i cant belive my truck stared today with out beein pluged in. ummm dumb question, i did notice too that if its really cold out and you dont wipe the snow off your truck and go drivin down th road it will frost up with all the snow blowin off your hood.

 

Ok, Will Try That. Has Anyone Used A Winter Front On An 06 And Does It Raise The Coolant Temp Enough To Improve Defrost In Bad Weather?

 

had this happen to me last week too... never in any vehicle before. got a smell like snow was hitting the hot heater core and boiling, which we know isn't possible, but the frosting isn't nice. makes me wonder if you were driving in heavy snow would it do the same??

to the OP, if you're driving in rain/freezing rain and it keeps fogging up, open a window or 2 just a crack...it always used to work for me.

 

driving in heavy snow iv never had any issues with fogging up, i was told thought one differance between the canadian f-150s and the u.s 150 is the canadian ones do have a better heater, like i noticed mine on this truck blow hot hot air like not nice to keep your hand over the vent hot. your truck is running about half way up on the engin temp gauge right ??

 

the needle is pointing straight up to the ceiling (twelve o'clock) in the white zone, and there is more white on the gauge up to about two o'clock before it would be in the red, so that suggests to me it would be ok to run it a little hotter if I wanted to by blocking off the air with a winter front cover over the grille?

 

Blocking off the front will only help warm the negine up faster when it is cold, the thermostat will open and close as necessary to maintain the proper engine temperature.

 

the thermostat is closed and no fluid is pumped anywhere until a certain temp...190F I believe. When it opens, then the water starts circulating.

Blocking the rad does nothing up to that point

 

The thermostat opens to allow coolant to flow through the radiator, when the thermostat is closed the coolant is circulated through the engine block and cabin heatr only. If the coolant did not circulate through the block constantly the coolant would boil at the cylinder walls and cause the engine to overheat. Blocking off the radiator prevents the fan from blowing cold air over the engine which is why it will help the engine warm up faster.