Technical Keeping the windshield from fogging up

Driving during the winter an d with the temperatures being cooler I am constantly wiping the windshield to keep it clear, especially when its cool and raining, much like today, my car lacks defrost and I have been looking for something to alleviate the occasional problem.

As I was researching alternatives I ran across this item, of course it is from the much maligned harbor freight, but it's cheap, works off a 12 volt accessory plug in and might just do the job.

Have any of you guys used anything like this in the past? HRP
12v Auto Defroster With Light

 

I think maybe Rain-X applied to the inside helps with that. Or spit, like we did when snorkeling!

 

I have no experience with that unit, but here in Canada, defrost is not really an option. However, I have always wondered how the Model A guys run defrost with that gas tank there.

 

Have not used, but in general, you need a ridiculusly large current to make any significant amount of heat with 12V. If it uses 10A for example it gives of just 120W, not much compared to proper electric heat fans for your home and such, pumping out up to a few thousand watts.

In a car the absolutely most sensible way to get heat is to use the waste heat in the cooling system.

 

On my '35 pick-up I open the windshield a bit and crack a door window open.....keeps the windshield clear, but it gets a bit chilly in the cab......if you have a heater, run a flexible duct from it to the windshield.....

 

I use Rain X anti fog.

 

Polish the glass with Barbasol Shaving foam. The classic one, not the one with aloe.

 

RainX

 

Word is that those HF units do have a seriously high amp draw. Here as where Goldmountain is a working defroster really isn't an option and is a must have if you plan to drive in cooler months.
Still for short term use for just a few minutes to keep the windshield clear it might work fine.

 

HRP, tried one of those few years back ( looks like the same one as I remember).... it was nothing to brag about.

 

I think the answer is airflow across the glass more than air temp. I have had vehicles with modern AC units where the ac went out you were still able to blow air on the windshield and keep it somewhat clear. I've had good luck with those "turbo" style summer fans,they look like a tube, placed where it will blow across your vision site. Not as good as a dedicated defrost with AC demist, but better than nothing.

 

No heater. HRP

 

Lots of dash plug in styles but designed for later model dasboards - plus, only focus on one area - Rain X defrost cloth better than nothing - one reason stopped using my '34 Plymoth sedan as commute ride - even high end ac/heat systems defrost have not worked well - need two peole to keep windshield wiped down - will watch here for gauranteed solution

 

Modern cars with AC, use the AC to dehumidify the air, and it really works great to defog a windshield. Just a heater, works, but not nearly as well.

I've put a fan next to the windshield on a couple that didn't have real defrosters, and it works pretty well. The blower for a boat bilge is what I used. It's ugly, but hey, that's life.

 

Air flow is the key. When I snowmobiled even in sub zero temperatures sometimes you had to open the face shield to get some air flow and defog it.

 

Yeah, those plug in heaters are less than useless, in all honesty. You might as well just eat a can of baked beans the night before you go driving.

Ultimately if the dew point is low enough, movement of air across the screen will cause the condensation to eventually evaporate, but if you hit a cool patch you've only got a few options- a rag, drier air (air conditioner) or a temperature differential to put the air next to the condensation above the dew point.

There's not a whole lotta space up under the dash, I know, but possibly look for one of the circular units like a Smiths or Clayton that plumbs to the vehicle's cooling system- idle a while and get a bit of heat in? Those were a popular fitment during HAMB-friendly years.

Phil

 

Just run with no glass...

 

That is the same design fan as I was talking about. They move much more air than the larger diameter cooling fans. I bought mine at a truck stop.

 

Had one like that in my truck when I got it. Basically useless. And I tried Rain X Anti-fog. Wasn't happy. Put in an old Ford heater and ran defrost tubes. Slow but worked.

 

Cold ,wet,damp and raining, that just don't cut it. HRP

 

Man,you guys are young!!!I remember most buses and trucks had fans mounted on the dash to keep the windshield clear!Looked like a small [6 inch dia]house fan.would see them in cars too in this part of the country. I'll let some other old timer explain stick-on "canadian windows"

 

That's as close to having air-conditioning I have ever had in any of my cars. When I pointed it at the windshield, it then became the defrost unit. Mount them up high so they can do both jobs. You can buy ones that also oscillate, so it feels just like one of them new-fangled new car air-conditioners!

 

Those things were called "frost panes". They were oval clear plastic panels that captured an air pocket between it and the glass. I'm sure I haven't seen one on a car for over 40 years now. Heaters are designed better now.

 

Actually, the real Canadian option is to just put away the car until spring. That is sometime in July.

 

Boat blower! Nice!

 

Vintage Air can help you on the cold and the warm front.

 

Crack open the vent windows, Rain x , Shaving foam (helps to a certain degree as does a clean windscreen) Wales is wet, I did once have an accessory fan that attached to the screen with suckers no heat, but the airflow helped clear the screen.

 

I have used a 12v hair dryer, yes it works on the drivers side, but dang noisy. Discrete.

 

So buy an old under dash heater, like a Tropic Air or Arvin, etc with the defrost ducts and run some ducts under the dash to the windshield. Thats how they did it in the 30's and 40's, so it must be traditional.

 

When I was younger and the widows fogged up it meant I was having a hell of a lot of fun!