Engine/Transmission (1998.5 - 2002) moisture build up on inside windshield

[firefighter]

what would cause a coating of frost to be on the inside of the windshield of my 2001 1 ton dully. Thanks for suggestions.

 

[RustyJC]

Are you running your defroster when this occurs? If so, the A/C compressor should be running which provides dehumidification of the air in the cab - it removes the moisture put into the cab atmosphere by the occupants' breath. The chilled, dehumidified air is then reheated by the heater core and sent to heat the windshield through the defroster ducts.

All it takes for frost to form is (1.) the dew point (a measure of moisture in the air) of the cabin air to be above the glass temperature and (2.) the glass temperature to be 32 degF or below. Check to see that warm air is coming out of the defroster ducts and that the A/C compressor is running when defrost is selected.

Rusty

 

[Tractorat]

My 1994 chrysler does the same thing. You probably have a leak somewhere. Windshield ? Read window ? Ive heard that if you turn on the a/c fan full blast and let it run for a while, it will then build up pressure in the cabin. You can then spray soapy water around the edges of the glass and find where it might be leaking. If you give this a try, let me know how it works.

 

[cerberusiam]

Defrost not one, AC not working, leak in the heater core. Some of the common causes.

A lot depends on environment and whether you are sitting in the cab while it is warming up. Not quite enough info to tell exactly what is going on.

 

[firefighter]

this happens overnight when it is cold.

 

[Tractorat]

Just like my chrysler. I would be surprised if it had anything to do with coolant.

 

[cerberusiam]

Humidity in the air is going to frost on the windshield when it gets cold. The glass will cool faster than the rest of the surfaces and cause frost to form on the inside of the windows if the moisture is inside the vehicle.

If your heater core is leaking that will leave moisture in the interior air when it is used. Should be able to smell coolant when that happens but sometimes it is subtle.