Hi everyone, I thought I would post on here before I really get into diagnosing what is happening on my new to me Rav4. Bought about 6 months ago and have had no issues until the weather here up in Canada got cold and I'm having a hard time keeping the windshield and side windows clear. I have to run the fan at 100% and have the defrost on "front" and sometimes ill turn on the "rear" defrost if the back window starts fogging up. The car will eventually "catch up" if I drive it long enough but for quick trips around its very frustrating and dangerous. I have taken out the cabin filter which was not very dirty and have read the manual to make sure there isn't something I am missing. I was thinking about flushing the heater core maybe to start? I was hoping someone could point me in the right direction, Toyota has sold millions of these things and there is no way they all do this... some sort of moisture issue. If I open a rear window a little bit it seems to clear slightly faster. Thanks for any potential help Scotty Kilmer Fam
If the coolant is low, that could cause this problem - definitely flush and replace antifreeze. Is the HVAC system blowing lots of air out of the windshield vents? You could have a problem with the "blend doors" that direct air through the heater core and into the cabin.
Finally, try running both the heat and AC (AC will reduce the humidity which causes the fogging) on recirculation mode.
ok, Thanks for the reply. Yes there is lots of air blowing out of the vents on the windshield. very strong and can barely talk inside the cabin haha. I will try the AC more often as well but I thought I read in the manual that if its below -10C that the AC would not come on, but need to check on that. Will check coolant asap
I did a coolant flush today. brand new Toyota super long life coolant and its topped right to the line. Still fogging up very badly today and its only -5C here. I noticed about 15 other Rav4s on the road and none had fog issues.
if it's below freezing, the A/C will stop periodically, or not come on AS MUCH, to prevent it from icing up.
Basically your car is not heating up enough. I would make a cover for the front radiator to deny air flow. Try that with a full cover. If the engine runs too hot put some holes in it to promote air going thru. This is the easiest remedy....this is what those big semi's do....but they have electric or air operated radiator shutters on the front end to keep the engine very..TOASTY...
ok. That is interesting. I feel like the heat is very warm blowing up on the windshield but just isn't clearing the fog/moisture. I will tape the Tv box from xmas to the front of my car lol jk
@dion
but the thermostat valve to the radiator doesn't open until coolant has reached operating temp. Until that point, the radiator and cardboard is doing nothing right?
The point of restricting the air flow of the radiator is to up the temp and also maintain a higher temp of the engine. The thermostat can be as closed as possible but the engine temp may never reach the operating temp because of the very low temp around the engine and air flow thru the radiator. Usually this happens because of extremes and not considered normal operating temperatures. Thats why i used the example of trucks using shutters in front of their radiators as the area of their radiator is so massive and so efficient its too efficient under super cool temps that the engine cannot maintain normal temps. Cars can fall into the same scenario depending on their design. No two cars have the same amount of radiator efficiency vs their engine size. Most have no problem as the thermostat controls the temp as well as the fan to keep the temp within whats speced as in 190--210 degrees. but as i said in extreme low temps..it throws the whole equation out. In some ways it reveals how well or how bad the car was designed when introducing sub temperature operations.
that still sounds dubious to me. If the coolant temp drops below operating, the thermostat shuts and the engine warms it up again. Radiator is out of the picture. Consumer engines are so small and enclosed, that air cooling plays such a tiny part. I've spent some time in the Rockies around -30C/-20F and cars are working fine. None are wearing cardboard.
Well think of it this way...if your driving and its so cold outside..the engine block becomes the radiator and dispenses heat...no matter if the thermostate is closed shut..the engine cannot get hot enough to open it. now even if it does open..then Super cold coolant comes in and then the thermostat closes again. repeating the cycle.
Now in my example this does not pertain to ALL cars..it just shows that they are not created alike and some show their efficiency and then some show their lack of. A factor is also the combustion efficiency as well. Older engines may not get as hot due to their inefficiency. As for cardboard...people use other items as in black tarps under the grill so you can't see them to make the same effect. All it is a method to preserve heat. better than what they would have without. I don't know if you noticed on class 8 trucks they have as optional air doors on their radiators...they can be electric or air operated to control or better term preserve heat in the radiator for better heating. Same idea but more sophisticated. Same idea applies here but a little more primitive under extreme cold conditions and is not meant to be permanent.
Yes I've definitely seen big rigs do it. Clearly it is an issue for them. I've just never seen a small car/truck engine that couldn't warm itself up. Thermostats don't snap wide open. They open gradually so the engine doesn't get a full dose of cold coolant.
As with anything online...without being there there are some questions I have..how hot is it in the vehicle? OP only mentions its hot at the defroster but stil it cannot defrost the window glass. Is that excessive moisture present and why does it not dissipate.? My only solution was to up the heat to counter these problems but is it the real solution? Without more accurate detail as to what is really going on its a guess at this juncture.
Does the A/C work properly? This is necessary for drying out the air.
Is there a source of moisture in the vehicle? Wet or damp carpet or items somewhere inside. Possible a water leak. Always knock the snow off your shoes, otherwise it'll melt onto the floor and end up on your windows.
I'm wondering if that could be part of the issue. Once I do press the AC button the car eventually starts to defog but can take quite a while. Also, ive never had a vehicle where I had to have the AC on all winter... In every car i've ever owned I would always leave it on windshield defrost/heat the whole winter. Might have to break down and take it to a mechanic/dealer. Just seems like something that should be small. Thanks for the reply.
The windshield defog setting should automatically start the compressor, but it has to be working properly. But check your manual to be sure.
The other possibility is that for one of several reasons you have excess moisture in your car - leaking weatherstripping, leaking coolant from the heater core, or such. If the only source of moisture is one person's breath, cracking a window should keep fogging down - fogging the side windows on a short trip is not a common problem.
Make sure when you select “defrost” the circulation is off and the AC is on full blast. Then the AC system and make sure it is running fine ( you get ice cold air).
ok I will try that. I think it must have something to do with the defrost not removing moisture as it should. Thanks
Did you make sure the re-circulation button is OFF? I have an '09 Rav 4 and live in Canada with no issues. Also, as soon as you switch the climate control to the defrost position, the AC automatically comes on to assist with removing moisture.
Hi Everyone, Just wanted to provide an update just in case anyone else ever has this same issue. The Fresh air/ Recirculate Damper or "door" was stuck closed. This is located above the blower motor and directly above the cabin air filter. I was able to pop it back open and now it seems to be operating properly with the hvac controls. Hammered it with some lube and will cross fingers. Went for a 30 minute drive in the rain/snow and could see out of all windows! Thanks for the suggestions guys