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Discussion Starter · #1 ·
We have a 93e conv. and for the first 10-12 miles of a trip it runs perfectly. Then the engine temp dial needle drops like a rock and mist - highly humid air - comes into the cabin and needs a window to be opened quickly to clear it. If you stop, just for an instant and turn off the engine, everything goes back to normal for another 12 miles. The mist has no odour and the engine coolant is fine.
IT'S DRIVING ME CRAZY!!
Anyone got any ideas?
 

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Did you check you coolant for odor? Just on the outside chance that the previous owner used water instead of glycol?

If the temp gauge drops this is cooling and or, heater box related.
 

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I agree that Silver's sensor theory is reasonable, and I'll suggest another possibility...

Perhaps there is something wacky with the thermostat, causing it to sort of snap open all at once flooding the motor and heater core with cold coolant. Though I think thermostats get more sluggish as they age, not quicker.

Is it very cold out when this happens? Also, do you have the manual climate control? Or the automatic kind with the digital thermostat?
 

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I'll defer but how does a sensor cause a physical mist inside?

Now, I am making the assumption that the thermostat is still an old fashioned manual spring of course.

But how would mist get in the cabin? It would usually be a failed heater core under the dash or perhaps coolant is being forced out and toward the fresh air intake. You could check if the filter is damp?
 

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Every see the movie, The Mist. Thats whats happening.
 

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Discussion Starter · #7 ·
Thought about the sensor, thermostat and heater core but the absence of odour and the fact that the engine coolant level stays the same is puzzling. We used the car on New Years Eve when air temps were around 50f and sure enough it started misting up after 12 miles. The auto climate control was set to 70f and was running heat so I reduced it until the a/c kicked in but that was just as humid - but cold!
A sensor problem makes sense as the system resets as soon as the ignition is turned off but where is the humidity coming from? Could rainwater be collecting somewhere close to the heater but then how does it get blown into the cabin?
 

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I used to be amazed in the tropics when the AC would come on and the whole plane would fill with a fog for a few minutes when you said no odor that is what came to mind. AC and humid air?

But?

Why would the engine temp go south at the same time. These systems are beyond simple logic. Or is the engine "warm up" for the cabin somehow coupled to this and the AC to cause it to .. how does outside temp and conditions affect this?
 

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Could rainwater be collecting somewhere close to the heater but then how does it get blown into the cabin?
There is definitely the potential for rainwater to accumulate - sometimes it gets past the cabin air filter - similarly, the drain for the condensation could be clogged. But it's hard to see how these would cause trouble at 12 miles or make the temp gauge plunge :roll:
 

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It is more likely a heater core issue. For the first 10-12 miles, your heater core is not warm, after it is warm and has expanded, where ever the leak in the line is shows itself, thus fogging up your windows. I've had this problem in my old chevy truck many-a-times. Once you shut down the engine, your coolant pressure drops and "stops the leak" momentarily. Restarting the car starts this process all over

It doesn't take a very big leak to cause this, and the coolant level may not have any noticeable change for a while
 

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Once you shut down the engine, your coolant pressure drops and "stops the leak" momentarily. Restarting the car starts this process all over

It doesn't take a very big leak to cause this, and the coolant level may not have any noticeable change for a while
This definitely makes sense, too. But if that were the case, wouldn't the smell of antifreeze inside the car be very strong??
 

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We have a 93e conv. and for the first 10-12 miles of a trip it runs perfectly. Then the engine temp dial needle drops like a rock and mist - highly humid air - comes into the cabin and needs a window to be opened quickly to clear it. If you stop, just for an instant and turn off the engine, everything goes back to normal for another 12 miles. The mist has no odour and the engine coolant is fine.
IT'S DRIVING ME CRAZY!!
Anyone got any ideas?
no a mystery ...... it is a defective temperature engine sensor; a porous in the sensor. when you start the engine look like normal but when water come into the sensor is equal no resistance by short circuit then the gauge temp drops.
you need to replace the temperature sensor.

foggy windows is another issue no relation with the sensor temperature.
is due to interior recirculation (turn off) and to solve this problem turn on the AC to dry moisture also heater windows and air exterior air recirculation. never interior recirculation.

happy new year!!!
 

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most liquids, once they convert to steam, expand their volume hugely. Like water expands 1400 times its original volume when in steam form. The same can be said for anti-freeze/coolant
 
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