2009 Yaris with ICE on inside of car windows

[CTScott]

As I mentioned in another thread about severe Winter window fogging, excessive moisture inside of the car is likely to blame. This can be caused by something as simple as having live bodies in the car on a super cold day and not extracting the moisture with the A/C or by some source of water in the vehicle. The water could be condensate trapped in the bottom of the airbox due to the drain hose being plugged (very common on Yaris if the cabin air filter is not installed in the slot behind the glove box). It could also just be moisture trapped in the carpet or seats.

Running the A/C along with the heat should help, but if it is carpet or seat moisture (from an accidental window left open during rain, etc.) running a household dehumidifier inside of the car on a warm (60F+) day will help to suck it out.

[jdennis187]

Originally Posted by CTScott

As I mentioned in another thread about severe Winter window fogging, excessive moisture inside of the car is likely to blame. This can be caused by something as simple as having live bodies in the car on a super cold day and not extracting the moisture with the A/C or by some source of water in the vehicle. The water could be condensate trapped in the bottom of the airbox due to the drain hose being plugged (very common on Yaris if the cabin air filter is not installed in the slot behind the glove box). It could also just be moisture trapped in the carpet or seats.

Running the A/C along with the heat should help, but if it is carpet or seat moisture (from an accidental window left open during rain, etc.) running a household dehumidifier inside of the car on a warm (60F+) day will help to suck it out.

It is 12 degrees in Albany, NY right now, so running the A/C is tough. But to clarify, are you saying that I could run the A/C and heat at the same time and that this would remove moisture from the cabin? Also, say the drain hose is plugged, would I be able to determine this myself without a mechanic looking at it? thanks!

[JustPassinThru]

Originally Posted by jdennis187

It is 12 degrees in Albany, NY right now, so running the A/C is tough. But to clarify, are you saying that I could run the A/C and heat at the same time and that this would remove moisture from the cabin? Also, say the drain hose is plugged, would I be able to determine this myself without a mechanic looking at it? thanks!

Yes, you can. In fact the defroster selection also turns on the air conditioning compressor.

It's a common thing to do on a damp, chilly day. A/C to dry the air, the heater core to warm you up.

[CTScott]

Originally Posted by jdennis187

It is 12 degrees in Albany, NY right now, so running the A/C is tough. But to clarify, are you saying that I could run the A/C and heat at the same time and that this would remove moisture from the cabin? Also, say the drain hose is plugged, would I be able to determine this myself without a mechanic looking at it? thanks!

When you have the knob on full defog mode the AC automatically runs. You can press the AC switch to have it run in any of the other modes, and it can be on with the temperature knob in any position. including full hot.

The AC condensate drain hose goes through the floor at the top left of the passenger side foot well. If you pull the carpet back in that corner you will see the black hose that goes through the floor via a molded on grommet. You can pull that hose up and (with a pan under it to catch what comes out) you can run something flexible up into it to clear any debris that is blocking it.

While you are doing that, open the glove box, squeeze the rear corners towards the center and remove the glove box. To the left, behind it, is the rectangular slot for the air filter. Pop the cover and see if one is installed. If not, grab yourself one at an auto parts store. No having one installed leads to stuff blocking the drain as well as eventual swampy stink from the AC.