Windows fog up uncontrollably.

[Chrisnick]

It sounds weird, but blast the heater. Once the condensation on the windshield collects, wipe a small bit with your finger. Taste it. If it tastes like coolant, it's your heater core. Chances are, it is your heater core as you've already had to replace one blower. When coolant gets on that stuff, it'll kill it pretty quick due to the extra resistance.

You're a car guy, you should know how to identify different fluids by taste/smell.

If it turns out to be a heater core, good luck. I've yet to do one on any car I've worked on that wasn't a total nightmare.

[Fleetw00d]

In my case, it would make sense that the appropriate action until the issues is corrected would be to not run the air conditioner at all.

Then again, if this is related to the heater core, then why does it still seem to present itself when the temperature is turned down low? I admit I don't run it cold because it's comfortable, but I've just tried to vary every single input on the HVAC unit to correct the issue. There have been times I've driven on these trips where the A/C has been blowing on full cold and I haven't noticed any change in the defroster. Isn't the heater eliminated from the equation at this point?

The heater valve only prevents flow of fluid to the heater core; it only blocks the inlet. The discharge is still open to the rest of the cooling system so that the heater core remains at the same pressure as the rest of the system. So if there is a leak, it will continue to leak (just not the hottest coolant) even with the heat turned off.

Depending on how hardy you feel and what the temperature is down there, you could bypass the heater core entirely by either disconnecting and plugging both heater hoses, or connect inlet to discharge with the valve still in line; just leave it "off" to prevent coolant flow through the bypass loop you've just created. This would also be a good test; if with it bypassed your fogging problem improves significantly, that indicates strongly that it is the heater core that is leaking.

[wagon-r]

you could bypass the heater core entirely by either disconnecting and plugging both heater hoses, or connect inlet to discharge with the valve still in line.

I did this once with one of the old beaters I used to drive in the 70s. Just ran a loop from inlet to discharge. A lot cheaper and easier than trying to replace the heater core. It was cold in the winter (I live in Michigan), but as long as I didn't drive too far, it was bearable.

[Jarrett]

Thanks you to everyone who has replied. I'll update this thread once I replace the heater core.

I drive this car twice a week, literally. I don't need it so badly that I need to loop the hoses going into the cabin as a placeholder. I'll just pull the dash when I take vacation. I've pulled the dash on these at least 10 times so it's very familiar to me. This may be a good time for a write-up? My girlfriend just got a new(to her) Nikon D5000 so this would be a great way to break it in.

[Fleetw00d]

I'll just pull the dash when I take vacation. I've pulled the dash on these at least 10 times so it's very familiar to me. This may be a good time for a write-up? My girlfriend just got a new(to her) Nikon D5000 so this would be a great way to break it in.

Good luck with the core swap. I only pulled one dash, from the 93 EX coupe that got hit in 2012; seemed like a job to avoid unless really necessary. Maybe I just went about it the wrong way.

[F22Chris]

Thanks you to everyone who has replied. I'll update this thread once I replace the heater core.

I drive this car twice a week, literally. I don't need it so badly that I need to loop the hoses going into the cabin as a placeholder. I'll just pull the dash when I take vacation. I've pulled the dash on these at least 10 times so it's very familiar to me. This may be a good time for a write-up? My girlfriend just got a new(to her) Nikon D5000 so this would be a great way to break it in.

Might as well get the cabin filter while you're in there, dude.

[Losiracer2]

FYI, the OE heater core is A LOT better in quality than an aftermarket one you find at O'Reilly auto parts.

I pulled my dash back in 2011 in my DD thinking my core was bad, only had to reshape outlets with a socket, and the replacement one was half the thickness or had half the amount of fins, I can't remember. But when putting them side by side, it was a huge difference, enough so that I reinstalled the OEM one back on after massaging the outlet ports finding out that was the only thing the matter with it.

[Jarrett]

Might as well get the cabin filter while you're in there, dude.

Accords didn't get cabin filters until 1998.

[illinois_erik]

Might as well get the cabin filter while you're in there, dude.

Yes make sure you gather up your eco friendly filter of leaves and other debris.


I wonder if theres a way to "tune up" the flap mechanisms, in the CD you hear them working well, my last CB you could tell they were messed up by how they sounded (air always blew out of the front)..the current CB ill have to dig in `cause the switch, resistor or blower motors gone out. The flaps sound ok, well they at least functioned right the little bit the blower did work. oh why i mention this is because in the summer if it rained itd fog up so bad id have to pull off and wait for things to equalize (windows down in the rain) or if lucky enough to be on the highway roll down the rears..even off in any mode, there was always heat coming out in the car with the messed up flaps.

[F22Chris]

Accords didn't get cabin filters until 1998.

:O I didn't know this.

[muhammedmian]

I know that air comes in through the vents on the bottom of the windshield and circulates out through the vent in the trunk. Maybe some port(s) are clogged up?

[F22Chris]

I remember somebody talking about how they used that expanding foam stuff that hardens on the air ducts to get stronger air flow.

[excalibur02]

I too have the same problem on my red sedan.

My car has been fine for the 2+ years I have owned it. Then on black Friday 2014. I had an ice sheet fly off a tractor trailer and shattered my windshield. I had the car sitting for about 3 weeks with the windshield because I went on vacation the next day to Florida. I got the windshield replaced and then smelled coolant and saw my windshield fog up every time the car was on. Mind you I'm in NJ and temperatures in winter were -5° to high of 30° F. My heat works fine and is very hot compared to my wagon. I cleaned the inside of windshield every so often. I noticed the windshield has a slight haze or film build up. I also noticed the steam coming from the vents also! I checked for a coolant leak and I actually did have one in the engine bay. It was from the top of thethermostat to under the throttle body. Fixed that but still have that coolant steam smell inside the cabin.

I don't think it's my heater blower as I said my heat comes out nice and hot and has never given me issues.

I almost think it's the new windshield that's giving me this problem. Since I never had this issue before with my oem windshield.

I have a lifetime warranty on the windshield seal but I would want to see if anyone else found a solution.

Thanks!

[Jarrett]

Yeah, it would be awesome if there were a way to actually test the heater core to some degree of certainty before actually completely ripping it out. The only factory service manual I have with me is for the European CC7 and it says that the evaporator must be removed in order to take out the heater box. That sucks.

[excalibur02]

Reading more about the fogging of the windshield and smell of coolant on Google searches, it's most likely the heater core.

I am considering removing the dash soon to fix this issue and replace the heater core, since this fogging up is driving me crazy.