I never use recirculated air except with A/C on. But then in the
Seattle area you seldom need A/C.

JP

it's relatively uncommon for heater cores to leak since they're not as

-------------------------------
Yep. John Paul, turn OFF the recirculator or you'll pump the moisture
from your floor mats onto the inside of your windows. Outside air is
bone dry, you want that instead.
You'd know all about this if you knew anybody who owned a Hyundai PONY.
Steam bath on wheels.  :-(

'Curly'

it's relatively uncommon for heater cores to leak since they're not as
exposed to damage.  if your condensation /smells/ of coolant, then it
may be leaking, if it doesn't, then it's not.  weather has been very
cold of late and windows will definitely fog up more.

Well, I'm afraid I did not have a choice at the time when I found my
radiator almost empty and use tap water to mix with the Prestone
antifreeze as premixed one was not available. I'm taking the car in to
my mechanic for 240 K scheduled maintenance (same as 60 K) and tell
him to drain the cooling system and refill it with premixed coolant.
As he deals with all kinds of Japanese cars, not just Honda, I am
making sure he is going to use Honda brand ATF which I bought
yesterday at a nearby Honda dealer's part store. I also bought new
spark plugs there and oil filter. As before I'll have him use the
Castrol 5-30 oil that I provide as he normally uses Chevron brand.

From the answers so far I have not seen many that addressed the
possible source of coolant vapor getting into the passenger
compartment and condensating on the cold windows. My first thought was
a heater core leak but that does not explain how the vapor gets in
with the heat turned off. I figure it must be a very small leak if it
does not create noticeable drop in coolant level or drips under the
engine. I'll see what the mechanic might find tomorrow but if he
suggest replacing the heater core I would hesitate to take that route
due to the big labor involved with it. In that case I might try first
to put that "Liquid Aluminum" radiator silant powder into the coolant
and see if that helps. On the other hand some of you would probably
say that it could hurt more than help. Any thoughts about it?

JP

That's the Elephant Containment Unit <8^P   No, wait! It's the Engine
Control Unit. Honda tucked it under the driver's seat for you (I believe
that's where it is in the '94 Accord) because they needed someplace to put
it. If it gets wet it is usually ruined, and that is the main reason for
having to replace the ECU. The symptoms range from running very badly to not
running at all, so you're in good shape on that.

That's really good to hear. I always get a sinking feeling when somebody
posts about their engine suddenly misbehaving or quitting and then they
reveal the timing belt is the original.

The Honda coolant is not as critical as the power steering fluid or the ATF,
but it's pretty cheap insurance against water pump seal trouble. Being
premixed, there is also no concern about it being diluted with tap water,
which is a very bad idea. Aftermarket thermostats, on the other hand, have
earned a reputation for flaky operation. I gave up on them about a decade
ago.

Mike

I hope you're right but what is ECU? Last time I checked it was some
European currency or something. ;-)

You are asking all the right questions.  That coolant was probably
getting to a dangerously low level even before that long commute
episode. Why do I think that? It is because when I think back now, the
radiator fan used to kick in after I stopped the car even after
relatively short drives and during cold weather. Now that I filled it
up with coolant, I don't see the electric fan starting up after
getting home in cold weather. Before this episode I thought it was
normal for the fan to kick in after getting to my garage, so I din't
pay much attention to the other factors, such as outside temperature
or how long the drive was. Now I notice it.

I have been taking my car to a pretty good independent shop
specializing in all kinds of Japanese cars but I never thought of
insisting on genuine Honda antifreeze premix or thermostat. The only
thing I insist is Honda premium ATF and Castrol 5-30W oil. As the car
has been running pretty well, I figured I did not need more than that.

Timing belt replacement is called for every 90 K miles which I have
followed religiously. My next one is due after 30 K more miles.

JP

Pilots speak of the engine being "auto-rough in clouds." I think the same
thing is bedeviling you. Your anxiety level is higher and things that you
normally wouldn't give a thought to are on your mind.

The first experience - stalling in deep water - is puzzling. Why the engine
stalled I don't know, but you should be aware the ECU can get wet when the
car is in water above the floorboards for a while. Vague, I know, but
different cars have different leakage rates. As long as your "check engine"
light hasn't been coming on and the engine runs normally you've probably
been on the side of the angels there.

The overheating is always a concern, since serious overheating can warp the
cylinder head and cause persistent overheating and loss of coolant. It's
safe to say you lost coolant at some point - you had to refill - but when
was the last time you checked the coolant level before this? It may have
dropped over the course of months or even years. Since the coolant isn't
disappearing now the other worries, like the condensation, really aren't
significant. Even when the heater core leaks the condensation is water (the
glycol is actually cooled by the fractional distillation of the water in the
mix). It's also hard to miss the sweet antifreeze smell of a leaking
radiator core.

If the coolant hasn't actually been changed recently, this is as good time
as any. It should be refilled with genuine Honda premix. Replacing the
thermostat with a Honda thermostat isn't a bad idea while that is being
done. And just to cover another very important routine as long as your
awareness is elevated: is the timing belt due for replacement? Your owner's
manual will tell you how often it's due, and letting it go can cost you the
engine.

Mike

This car still runs great with 240 K miles in it but recently I had
some bad episodes which makes me wonder.

The first episode was about a month ago when I was driving at night in
a heavy downpour and I ran into a deep puddle that I could not see in
time. The puddle may have been about axle deep at its deepest point
and the engine suddenly stopped. When the car itself stopped rolling
it was still in the puddle but in only about ankle deep at that point.
Fortunately my electric circuits seemed to be OK as I was able to use
the emergency flashers. As I was ready to phone for some help, I
decided to see if I could start it. Well, the starter seemed to have
plenty of power and after several cranking attempts I was able to
restart the engine and except the initial spongy brakes everything
seemed to be fine.

I still have no idea what caused the engine cutoff: water getting to
the ignition circuits or perhaps into the air intake? I always thought
Honda's electric circuits were pretty well insulated from moisture,
with tight rubber boots, etc.  But maybe somebody has a better insight
into this.

The second episode was about 10 days ago when the normally 30 minute
home commute turned into 4 hours because of a snow storm hitting my
area just at the afternoon commute time. At the end of four hours I
could not even make the last two miles on the side streets so I had to
leave my car overnight at a supermarket parking lot for two days till
the side streets were good enough to drive it home. Later that day I
drove the car on the freeway and I noticed that the temp. guage was
moving really fast to the top that I never noticed before. So I
quickly pulled off at the nearest exit and checked my coolant at a gas
station. Sure enough, the radiator was almost empty as I could pour
about 3 quarts of antifreeze mixture into it. Since then I've been
watching any leaks in the cooling system but could not notice any and
its level has been holding in the radiator after several days. I still
wonder though if I was driving with low coolant level and high engine
temp during some of that long 4 hour commute but I was just not
looking at the guage. The car is still running fine but again it makes
me wonder.

It makes me wonder especially as I noticed the unusually heavy fogging
in my car after the engine warms up and especially when I turn on the
heater.  I get a lot of condensation on the cold windows, even on the
rear window. The condensation does not seem to be pure water but feels
slick like the antifreeze. What is puzzling about it though that I
don't seem to be losing any coolant as far as I can see in its level
visible in the radiator opening. I also see no drips on my garage
floor.  It's a real mistery to me.

I am taking my car to a shop next week but would appreciate  hearing
any insights from those of you having had more experience with cars
than I've had.

Thanks for reading this long post,

JP