DIY Electric Car Forums banner

Fogged Windows from ceramic heaters mounted in silicon?

1404 Views 4 Replies 4 Participants Last post by  gdirwin
My RAV4 EV has developed bad fogged windows - I am very familiar with cold weather/frost buildup etc... from normal ICE driving (including anti-freeze from a bad heater core causing the rainbow effect etc...) - this is something else.

I have 2 ceramic heating elements and use an AC warmer before I start driving, so lots of heat. You can pour heat on the windows for hours, warm or cold weather - no difference.

I tried cleaning the windows with different types of window cleaners (including the good foam types) - stays clear for 1 or 2 days, then the fogging is back.

The most likely possibility:
- my ceramic heaters are imbedded in the old heater core, with a tremendous amount of high-temperature silicon - perhaps the heat has affected the silicon and is gassing?

The film seams oily like - consistent with silicon...

Another (very remote) possibility is that somehow my charger is releasing a gas of some sort - it is mounted on the inside of the car and has an exhaust fan.

Anyone else seen anything similar?

It's a real pain cleaning the windows every day...
1 - 5 of 5 Posts

· Registered
506 Posts
Yes, your silcone is gassing, matter of fact there are plastics in vehicles that do the same thing when vehicle left in the sun in the summer time. I've also noted that some steering wheels get sticky.

To be honest those plastics gassing concerns me enough to were I always leave my window cracked a bit while driving or parked in the sun for any lenght. I also keep my home ventilated for the same reason. Anyone that has ever opened a box with a monitor or tv in it, should know how much those items gas.


· Registered
1,199 Posts
A possible contributing factor.

Is your heater in recirculation mode or fresh air mode? If you are running in recirculation mode, everything will build up, moisture, tobacco fumes, plastic outgassing, etc. Check the owners manual to be sure. If you have a vacuum switching system and it is disabled, quite often the default position of the heater is recirc and defrost.

If the recirculation mode is the problem and you get low heat with fresh air heating I can only suggest try finding a happy medium by locking the fresh air/recirc door in some middle posiion.

Saw a few cars come into the dealership where water was dripping from the headliner because the owner ran in recirculation mode all the time.

· Registered
309 Posts
Discussion Starter · #5 ·
I have seen this before too (from ICE experience) - I am sure the re-circ button is off, so I should be getting fresh air. The gate seems to be to electrically driven, as I do not recall any vaccuum lines. When I hit the recirc button (by default it is off) I can feel a change in the airflow - so I think it is working. An important aspect though, so will double check.

I do not think this is the problem though - once it is fogged, I have opened all windows and it does not clear. There seems to be an oily film on the inside - I clean the windows (squeeky clean) and it is back 1 day later!

I am now trying to narrow things down:
1) charger exhausting into the car
2) silicon gassing from the interior heater
3) something from my 120VAC interior heater...

Place your bets!
1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.