[Alex_O]

Hello.
2014 VW Passat SEL TDI
I’ve noticed sometimes a car could be super fast fogged up with lots of condensation inside. It happens quickly and no any warning indication on the dash board. Also airflow to the windshield is weak.
Any suggestions how to fix this? (Cabin filter just has been changed, unless it was a bad one and I need to get another brand)

Thanks

 

[Rob Craig]

Hello.
2014 VW Passat SEL TDI
I’ve noticed sometimes a car could be super fast fogged up with lots of condensation inside. It happens quickly and no any warning indication on the dash board. Also airflow to the windshield is weak.
Any suggestions how to fix this? (Cabin filter just has been changed, unless it was a bad one and I need to get another brand)

Thanks

Could be a leaky heater core. Is the fog hard to clean off? Also check if condensate drain tube is plugged.

 

[csigona]

Hello.
2014 VW Passat SEL TDI
I’ve noticed sometimes a car could be super fast fogged up with lots of condensation inside. It happens quickly and no any warning indication on the dash board. Also airflow to the windshield is weak.
Any suggestions how to fix this? (Cabin filter just has been changed, unless it was a bad one and I need to get another brand)

Thanks

It could be a leaking heater core, like Rob Craig says. If it's the heater core that's leaking, it's coolant. Try to wipe the condensation off the windshield. If it's thick or oily, it's probably coolant. It it's easy to remove, it's plain water, so look for outside water leaking into the area where the blower is. Since you say it's sudden, could it be ice that melts as the area warms up?

My bet is on Rob Craig being right.

 

[sbernardin]

How dirty was the cabin filter? Were there leaves and other debris in the filter compartment? Check whether the AC compressor is running when you have the Defrost selected on your climate control. If you run your system on Recirculate Mode, the windows will fog unless you bring in outside air, unless the AC is also running. With the AC running the dewpoint is lowered so fogging is not usually an issue. Is your vehicle parked outside, under trees? If so, you might want to check the cowling area under the plastic cover for debris and also plugged drainage areas (usually at the fender sides of the cowling.

 

[amtruckn]

If it is a coolant leak you will smell the coolant. I'm not sure if it's common amongst all VW's but my 2001 Jetta when you select defrost it automatically opens the vent for fresh air.