C5 mk1 steam/frost problem

[Tuho]

I have a Citroen C5 mk1 exclusive estate wagon 2001 with no sunroof.

It has a weird steaming/frosting problem. The windows of the car start to steam when you start driving. Sometimes the steam appears immidietly after starting the car.

When idling stationary the steam starts to disappear, but comes back as soon as you start to drive. I have noticed that there is a weird smell (not like coolant) first when driving and then the steaming get worse. I have also noticed that this happens mostly when accelrating.

When the weather gets cold (under 5 degrees celsius) the steam/frost problem gets really bad.
If the weather is really cold (like -20), the steam frozes in to the glasses and makes the driving almost impossible.

In the summer when weather is more than 5 degrees celsius it steams the windshield breafly only when you start the car.

I dont believe it could be the heater cell because if it would be coolant on the glasses it should not froze and there is no smell of coolant and the coolant is not disappearing at all.

Pollen filter is new.

Indoor air circulation flap has been checked by Citroen service and it is working according them. Circulation is off.

Condensation water route on the right side of the car is open and it's dry.

Car does not have wet floors at least from the surface.

What could be the problem?

[GiveMeABreak]

Check the drain holes either side of the vehicle under the wheel arches where the water can accumulate under the scuttle area when these get blocked up with leaves and other muck. Also check the drain holes at the bottom of the doors are unblocked.

[white exec]

Agree - it has to be dampness/moisture/humidity in the cabin, that ends up on cold windows as condensation.
Most coolants do have a smell, but not all. Check the footwells and under the floor mats.
Check also any floor pan rubber grommets that might have gone missing.

[Tuho]

Check the drain holes either side of the vehicle under the wheel arches where the water can accumulate under the scuttle area when these get blocked up with leaves and other muck. Also check the drain holes at the bottom of the doors are unblocked.

I did not really understand where there are drain holes under the wheel arches. Is there a photo where I could see what you mean?

Agree - it has to be dampness/moisture/humidity in the cabin, that ends up on cold windows as condensation.
Most coolants do have a smell, but not all. Check the footwells and under the floor mats.
Check also any floor pan rubber grommets that might have gone missing.

Weirdest thing is that the steaming is not coming continually all the time. That's why I don't think it's huminity in the cabin.. The footwells are dry under the floor mats, and I can't find huminity anywhere in the cabin.

Usually it takes its place when accelrating. There is a smell first and then the air coming inside turns humid and the windows start to get steam.

When idling stationary there is no steam. If I stop the car when it has steam on the windows, it takes only few minutes and the steam is gone.

Could there be water leaking in to the fan housing which is then moving when accelrating?

I also suspected the heater core but Citroen dealer service said that they don't believe it's the heater core/radiator.. I have driven 15 000 km with it and no coolant loss so I guess they are right. Also the steam frozes in to the glasses when the weather is cold, coolant does not freeze..

[white exec]

Air con (cold heater matrix - evaporator) drain blocked?

[Tuho]

Air con (cold heater matrix - evaporator) drain blocked?

Where is that exactly?

The drain which is on the right side of the front of the center console is open and dry but I don't even know what drain that is..

[GiveMeABreak]

That's not a drain - I think you are referring to one of the interior air temperature probes (if it's a small round grid on the fascia).

Check your water evacuation pipe. It is on the right side of the heating unit (not visible inside the car) where the tube runs underneath the vehicle and allows the condensed water to drain out under the vehicle onto the road. If this is blocked, you'll be getting excess water inside the unit.