Windshield fogging

I had the leaking heater core replaced about a year ago in my '94 Honda
Accord LX but the windshield started fogging up again in cold days and
nights about a month ago. Not as much as it was before that heater core was
replaced, but it still concerns me. Though the condensation is slick and
film like, I don't see any noticeable loss of coolant under the radiator cap
or the overflow reservoir. I am at a loss in figuring out what else could
cause such a fogging. I hope it's not some micro leak in the heater core
again after such a short time and expensive repair.
I also noticed that the fogging happens almost exclusively just above the
two center vent holes at the base of the windshield and hardly at all at the
left and right hole. By the way, I am NOT using the recirculate position of
the air flow control, so that possibility is out.
Any suggestions?

Thanks,
RP

 

Check to make sure the fresh-air intake part of the thing is actually
working. I had some work done on a car years ago and had fogging
problems. It turned out that they had not put it all back together
properly, such that the door that was supposed to bring in fresh outside
air was never opening. Just a thought.

 

Noted, but would that explain the filmy fogging?

Thanks,
JR

 

Be sure that all the remnants of the old leak are removed from the
windshield. Also, there are anti fogging agents available in your FLAPS.

JT

 

I took it to a good mechanic who found the heater control valve not closing
completely and letting hot coolant into the heater core even when the valve
was set to closed position. I don't know how this could effect moisture
getting into the air vents but it looks like the replaced control valve
fixed the problem. Go and figure ...

R. P.

 

Two main suspects for excessive windshield fogging are:


a) Remnants of anti-freeze from a leak, (previous or otherwise)

b) Remnants of vinyl deterioration from heat/age


Both can drive you nutz...

 

That may be so, but in my situation it did not appear to be the case.

RP