Climate strange problem.

[COSTASP]

I own a 1998 w140 s280 and I ve noticed something strange.
Whenever travel in rain or wash the car, the following happens:
I turn on the climate, it works normally and after a few seconds I hear
a noise like a wistle and the climate is almost blowing no air. When I press the
recirc button It works normally. After 1-2 sunny days the problem is gone.
What to do to solve it out?

 

[television]

I would check the water drain holes in the heater air intake box just in front of the screen.

 

[wireman]

Does it have a pollen filter ? it may be worth checking that its not getting blocked or soaked in the water which should drain out.

It would be good advice for all of us to check the drains on our cars, its becoming that time of year when leaf fall gets into them and blocks them.
Blocked body drains can cause some horrendous rust problems and if water gets into the floor and carpets it will smell and can damage the wiring loom, something you do not need to happen.