Fog in my face

[DonsFords]

I have a 99 Explorer Sport SOHC. When I turn on the defrost the entire windshield fogs up then begins to clear. This has been happening since about the time the warranty ran out. I am the only owner. It is a safety issue sometimes. I do not believe it is a leak in the evaporator or heater core. I am not loosing antifreeze/coolant or refrigerant. This seems to happen more in the spring and fall.

 

[JDraper]

I know you say you don't think it's a heater core, but that's the most common cause. A very small pinhole can cause fogging while not releasing much antifreeze.

 

[ronin2501]

The only reason it would fog up is an introduction of moisture. I think the heater core is probably what you are looking at. Fortunately it sounds like the leak is small enough you might get away with using a simple radiator leak stop.

 

[DonsFords]

It probably is in the core. It's just that it does not leave a film on the glass or an odor. That is what I have experience with my 71 Comet GT and 84 T Bird. I thought maybe it had something to do with the A/C compressor cycling ,or not,leaving moisture on the evaporator. It fogs then starts to defrost right away. No problems after initial defrost.

 

[IZwack]

Dunno where you are located but this is normal in the fall or in humid conditions when moisture condenses in the vent tract (for example: overnight)
Posted via Mobile Device

 

[Joe Dirt]

I was going to say what IZ did- my vehicles all do this from time to time, and none of the m have HC leaks. If it's a immediate fog for about 5-10 seconds that clears from the bottom up as "fresh" air hits it, that's what I have even in my '07 Camry... Been doing it lately as the weather changes to fall with big temp swings.