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View Full Version : What the fog!!!!!!


acon40
12-11-2007, 09:39 PM
Why the hell is my truck fogging up so bad? It seem the defrost will help keep it clear somewhat, but the truck fogs up so bad. My rear window needs to be swapped out s I know this is a must. But when its cold it fogs up SO BAD> anything I am missing. Its a 95 fj80.

Uncle Ben
12-11-2007, 09:43 PM
Does it smell like antifreeze? Is the AC coming on in defrost? (it should be)

Rezarf
12-11-2007, 09:45 PM
Wet floors can cause this too. Lots of water on your floor seem to aid in the steaming process.

Drew

Man Jerk
12-11-2007, 09:49 PM
Do you have it sent on outside air or recirculate? Recirculating the air will cause bad fog as well.

acon40
12-11-2007, 09:56 PM
No wet at all. I will keep an eye on the ac. if that does not click on when I hit defrost whats the deal?

acon40
12-11-2007, 09:57 PM
Oh an Ive nothing outside helps.....somewhat

nakman
12-11-2007, 10:17 PM
How many dogs are in the truck?



:)

Uncle Ben
12-11-2007, 10:32 PM
Often if a heater fogs the windows it is due to a heater core leak. I haven't done one on an 80 but I'm guessing it isn't too bad....but then again.... A/C comes on with defrost to dehumidify. If it isn't coming on does it work normally?

subzali
12-12-2007, 07:03 AM
Oh an Ive nothing outside helps.....somewhat

Not sure what this means, but easiest thing like Man Jerk said - check to see if somehow the air is getting bumped to recirculate - I almost never have mine on recirc (only through tunnels and very little else).

60wag
12-12-2007, 08:26 AM
Are you sure the rear carpet is dry? I had some fogging issues that turned out to be a tiny leak through the window trim mounting clips in the back near the gas filler pipe.

Romer
12-12-2007, 08:31 AM
This is common in an 80 based on threads on Mud.

This happens with my truuck as well.

My windows always fog when the air is set to recirculate rather than outside when its cold.

A quick way to defog is turn on the AC. This does not mean cold air. Have the temp up high and turn on the AC button. This will quickly add moisture to the air while still blowing warmer air.

Uncle Ben
12-12-2007, 08:31 AM
Not sure what this means, but easiest thing like Man Jerk said - check to see if somehow the air is getting bumped to recirculate - I almost never have mine on recirc (only through tunnels and very little else).


On an A/C equipped vehicle it needs to be on recirc on defrost as the purpose of A/C in a defroster circuit is dehumidification of the interior not the outside air!

Shark Bait
12-12-2007, 08:42 AM
Coming home from a scuba diving trip this past January, it was really cold outside and we had the rear of the 80 full of wet gear. I had the system on recirculate cause I figured we'd get more heat. The windows kept icing up from the inside!! It was a constant battle with the scraper. :) Took a while to figure out we were better off pulling in outside air. We laughed pretty hard. :lmao:

Romer
12-12-2007, 08:42 AM
On an A/C equipped vehicle it needs to be on recirc on defrost as the purpose of A/C in a defroster circuit is dehumidification of the interior not the outside air!


Doing this always fogs my windows, I go to outside air and it does not

Uncle Ben
12-12-2007, 08:49 AM
Doing this always fogs my windows, I go to outside air and it does not


Interesting! I go out and start the truck, push the defrost button (which by default activates A/C and recirc) and in >10 minutes my windows are clear.

Romer
12-12-2007, 08:58 AM
Interesting! I go out and start the truck, push the defrost button (which by default activates A/C and recirc) and in >10 minutes my windows are clear.

That's probably the difference. Your AC activates when you turn on defrost, mine currently does not. I mentioned above that's one way to get rid of the fog. Does your setup have the Auto feature and is it enabled? Auto being you set the temp and function and it sets the fan speed and other stuff.

Uncle Ben
12-12-2007, 09:01 AM
That's probably the difference. Your AC activates when you turn on defrost, mine currently does not. I mentioned above that's one way to get rid of the fog. Does your setup have the Auto feature and is it enabled? Auto being you set the temp and function and it sets the fan speed and other stuff.

Yesir....Climate control like yours with a new sensor and the sensor tube is attached.

Rezarf
12-12-2007, 09:12 AM
I have an Absorber towel in my 40 for when my windows fog up. It works really well :D Sometimes I keep a plastic scraper handy for those really icy days.

Drew

Romer
12-12-2007, 09:20 AM
Yesir....Climate control like yours with a new sensor and the sensor tube is attached.

I turned the auto feature off because it blew too hard in the summer. I like to adjust it myself. using the outside air works the majority of the time and when it doesn't I just turn on the AC like I mentioned above.

Now the majority of 80's don't have that feature if I recall and they would not have the AC auto engage when you turn on the Defrost, is that true? Someone with a non collectors 80 care to comment.

When I go home I will engage the auto feature and then turn on the Defrost and see what happens. I expect it will operate like yours.

subzali
12-12-2007, 02:34 PM
UB - I've been thinking about that for a little while now. Doesn't the air just get passed over a coil to heat it up for the defroster? Heating air ALWAYS dehumidifies it, and cooling air ALWAYS increases the density which increases the humidity - thus you see water dripping from air conditioners because they are condensing and removing that extra humidity. I need to look at why the refrigerant operating (A/C on)(normally used to cool the air) would help dehumidify when the heat is cranked up when it normally increases the humidity when it's being used to cool the air...

Uncle Ben
12-12-2007, 02:57 PM
UB - I've been thinking about that for a little while now. Doesn't the air just get passed over a coil to heat it up for the defroster? Heating air ALWAYS dehumidifies it, and cooling air ALWAYS increases the density which increases the humidity - thus you see water dripping from air conditioners because they are condensing and removing that extra humidity. I need to look at why the refrigerant operating (A/C on)(normally used to cool the air) would help dehumidify when the heat is cranked up when it normally increases the humidity when it's being used to cool the air...

You almost answered your own question. As the heated air passes through the AC evaporater the moisture gets stripped off by the cold fins. (much the same reason your window fogs!) It drips out the bottom of the truck instead of blowing back on the windshield. If you have access to an ACed vehicle that you can disengage the ac when on defrost then experiment. Crank on the defrost without the AC on. As soon as the window starts thawing the rest of the windows condense because of the cold window and warm moist air....now hit the ac.....fog will disappear in seconds!

subzali
12-12-2007, 03:23 PM
Well that's why I'm confused...my red truck has A/C and I've had it blowing "defrost" (maybe I'm getting confused by the terminology - or maybe newer vehicles have more sophisticated systems) - had the lever on the little defrost symbol - which focuses all the hot air onto the windshield - every morning lately, with no fogging. But maybe the A/C will enhance the drying effect...I'll check it out tomorrow.

60wag
12-12-2007, 04:13 PM
Umm.... close but not quite. Heating the air increases the capacity of the air to hold moisture - The RH goes down if the amount of moisture is held constant. By chilling the air across the evaporator coil in the AC, the RH exceeds 100% and water condenses out. So the moisture content is no longer constant. Once the air is then heated by the heater core, the RH is lower than is it had never passed by the evap coil.

As for inside vs outside air...... usually the outside RH is lower than the inside RH so I'd leave the recirc off, if you can.


edit: oops, I guess I should have read page 2 first.

acon40
12-12-2007, 09:07 PM
man do i start some threads. My ac does NOT come on in the 95 cruiser. My question is can i swap out my setup for a auto climate setup. I tend to battle the setting nonstop and i am sick of it.

On a side not i have used the rain x fog solution and it worked GREAT on my last truck so i will try it and report back.

SteveH
12-13-2007, 08:12 AM
Leave some windows open a few inches in your garage, or outside on a sunny day. This will dry out any accumulated moisture. Remove the floormats and let the moisture under them dry out, as well. This works well in Colo. where the humidity is so low - not so well in wetter areas. I never use recirc., as it fogs up the inside fairly quickly.

Rezarf
12-13-2007, 09:15 AM
Leave some windows open a few inches in your garage, or outside on a sunny day. This will dry out any accumulated moisture. Remove the floormats and let the moisture under them dry out, as well. This works well in Colo. where the humidity is so low - not so well in wetter areas. I never use recirc., as it fogs up the inside fairly quickly.

Good tip, I have done this and it helps.

Drew

corsair23
12-13-2007, 03:17 PM
man do i start some threads. My ac does NOT come on in the 95 cruiser. My question is can i swap out my setup for a auto climate setup. I tend to battle the setting nonstop and i am sick of it.

Confirmed on my trip in this morning that when I hit the defrost button (full defrost, not the defrost/floor mix button) my AC comes on and the HVAC systems switches to "fresh air" mode. FWIW

As to your question about the auto climate setup...Here is a MUD thread on this very thing and the answer is, I believe, yes but it is probably more work & $$ than it is worth --> Auto Climate Control MUD Thread (http://forum.ih8mud.com/showthread.php?t=31800)

The manual to auto swap is lower down in the thread.

That said, I'm not sure the behavior of the defrost/AC/fresh air has anything to do with the auto climate control or not :confused: - Honestly I never even use the auto climate control feature in the LX - although sliding the temp selector will give you way more fan speed settings in auto mod than the 4 (IIRC) you have today...Kind of like an adjustable ceiling light slider deal that will brighten and dim lights. Anyway, when I did my test this morning I didn't have my HVAC controls in auto mode. Not sure how it behaves in auto mode?

I can tell you if you from experience though if you don't have the "temp sensor" plugged into the HVAC unit you only have two choices for temperature...Full hot or full cold. If this is the same sensor that the MUD thread mentions (didn't read it all the through) as needing for the manual to auto swap then...well lets just say it won't work well without it :o

acon40
12-13-2007, 08:36 PM
You know what. I am over it. I will just buy the anti fog stuff hahaha $4 well spent.

Uncle Ben
12-13-2007, 08:58 PM
Confirmed on my trip in this morning that when I hit the defrost button (full defrost, not the defrost/floor mix button) my AC comes on and the HVAC systems switches to "fresh air" mode. FWIW




Noted mine today is the same as you describe. Defrost button selected, AC comes on and outside air door opens...... :rolleyes: Off of original topic but when I got my 40th the CC was less than good! After fiddling with it I discovered the hose floating behind the dash....which I put back on the sensor bung. It worked much better but still was not even close to the temp ranges so I replaced the thermistor with a new one from Toy. That did the trick and my CC works very well! Sprayed the evaporator with a can of Frigi-fresh Robbie gave me this summer and it was spooky haw much black muck ran out of the drain tube! I will definitely do that to a higher degree next spring!

Soooooo....back to the topic at hand....Acon, have you had any solutions yet from this banter? :rolleyes:

Uncle Ben
12-13-2007, 08:59 PM
You know what. I am over it. I will just buy the anti fog stuff hahaha $4 well spent.

Smart band-aid!