Rear Window Fogging - new idea?

Hi All,

Welp, the mornings are now going down below dewpoint solidly. Solong summer. And the rear window fogging issue is with us again.

So, while out doing a mouse inspection, I had an idea. Maybe somebody else has had this idea. Some of you may know about the fender vents in the Gen II Prius. These are rubber flaps that cover a plastic grillwork that covers a hole on the inside of the fender well. On the right side, the exhaust heat vent from the battery leads to grill. On the left side there is the rubber flap and grill down under/behind the storage comparment.

Might it be possible to get that vent to exhaust air from the rear deck area?

In stock condition the vent is all sealed off from flow.

But what about taking off the light bulb service covers. From that cavity its a straight shot down to these vents. So, if the taneau cover was retracted, and these covers removed, maybe we can get more flow down across the rear window?

While writting this I just realized the rubber cover is going to be held shut by air pressure. So, maybe it can be propped open with something --- tomorrow is another day...

 

Hi All,

Welp, the mornings are now going down below dewpoint solidly. Solong summer. And the rear window fogging issue is with us again.

So, while out doing a mouse inspection, I had an idea. Maybe somebody else has had this idea. Some of you may know about the fender vents in the Gen II Prius. These are rubber flaps that cover a plastic grillwork that covers a hole on the inside of the fender well. On the right side, the exhaust heat vent from the battery leads to grill. On the left side there is the rubber flap and grill down under/behind the storage comparment.

Might it be possible to get that vent to exhaust air from the rear deck area?

In stock condition the vent is all sealed off from flow.

But what about taking off the light bulb service covers. From that cavity its a straight shot down to these vents. So, if the taneau cover was retracted, and these covers removed, maybe we can get more flow down across the rear window?

While writting this I just realized the rubber cover is going to be held shut by air pressure. So, maybe it can be propped open with something --- tomorrow is another day...

 

Hi Seasalsa,

Well, this morning I turned off the climate control, as body heat was plenty to keep the passenger comparment warm, and using the heater slows down the warm up cycle. I think the car needs a heat off button, just like it has a an AC off button. But, later in the year the same problem happens even with the climate control on. Not till it gets down below freezing is it less of a problem. As the air gets drier.

Takes forever on my morning run to get clear rear glass. Not until there is air flowing through the car at highway speed does it clear up. On the 40 mph secondary road its fogged for the whole 4 miles. A few minutes on the highway at 60 mph and its clear. Opening the rear windows a crack has little effect. Seems the air back behind the rear windows is in a stagnant zone.

Getting some air to flow out right near the rear window should improve things. One could open a rear door window, and get air to flow in that window, over the hatch glass and out the vent. Front passenger comparment would stay warm, and hatch glass would clear.

Windshield only had a little condensation, which cleared due to the ventilation in less than a mile. But the rear window stayed covered with condensation for about 5.

 

Hi Seasalsa,

Well, this morning I turned off the climate control, as body heat was plenty to keep the passenger comparment warm, and using the heater slows down the warm up cycle. I think the car needs a heat off button, just like it has a an AC off button. But, later in the year the same problem happens even with the climate control on. Not till it gets down below freezing is it less of a problem. As the air gets drier.

Takes forever on my morning run to get clear rear glass. Not until there is air flowing through the car at highway speed does it clear up. On the 40 mph secondary road its fogged for the whole 4 miles. A few minutes on the highway at 60 mph and its clear. Opening the rear windows a crack has little effect. Seems the air back behind the rear windows is in a stagnant zone.

Getting some air to flow out right near the rear window should improve things. One could open a rear door window, and get air to flow in that window, over the hatch glass and out the vent. Front passenger comparment would stay warm, and hatch glass would clear.

Windshield only had a little condensation, which cleared due to the ventilation in less than a mile. But the rear window stayed covered with condensation for about 5.

 

Hi Seasalsa,

I did use the automatic temperature control on the drive home the night before. I just turned it off at the beggining of the morning drive. It was sunny, dry and about 75 degrees during the drive home the night before. The dewpoint was in the mid 50's, and the temp went down to 50 overnight. This morning the temp is down to 43. Dewpoint is probably 50. This is quit dry air.

No, I tired to avoid using the rear window defroster, as there was no frost. My past experience with it in these conditions is it would half the defogging time. Because the temperature is so warm, and its intended to get the glass above freezing, primarily.

I am just looking for a synergistic way to get rid of the fogging, that saves gas too.

 

Hi Seasalsa,

I did use the automatic temperature control on the drive home the night before. I just turned it off at the beggining of the morning drive. It was sunny, dry and about 75 degrees during the drive home the night before. The dewpoint was in the mid 50's, and the temp went down to 50 overnight. This morning the temp is down to 43. Dewpoint is probably 50. This is quit dry air.

No, I tired to avoid using the rear window defroster, as there was no frost. My past experience with it in these conditions is it would half the defogging time. Because the temperature is so warm, and its intended to get the glass above freezing, primarily.

I am just looking for a synergistic way to get rid of the fogging, that saves gas too.