Hi,

I have a C200 1998 and during the recent heavy rainfall here in the UK and parking under trees I have found water leaking onto the passenger's side floor.
Added to this my windscreen is contiually steamed up as the heater is not demistifying the windscreen.
On inspection I removed the heater lower motor from the panel below the gloce compartment. Water poured out of here as it appears to have been trapped there, hence the lack a decent hot airflow in the car.
The housing above where the heater is looks clear, so can anyone help as to where this water is coming from. As far as I can see between the windscreen cowl and the engine there does not appear to be any blockage (yet?).

Thanks

K

 

Hi,
There is a drain in the plenum chamber immediately in front of the windshield. This drain gets blocked and causes the water to collect and then cascades into the fresh air inlet and into the blower motor as you have found.
There is also a drain(s) in the bottom of the evaporator box in the heater unit. this is intended to drain condensate from the air con evaporater.

Misting up is the classic signal that a drain is blocked and with luck signals the situation BEFORE the carpets get wet.

The plenum drain gets blocked with pine needles and leaves. it is important that it is cleared at least at every service, preferable more frequently.

Clear the drain, dry the car out using the air con Oon max (recirc operating) + heat so that you don't freeze. It is very effective since it takes water out of the car.

Hope this helps you understand what has happened.

 

Thanks for that,

I dried the car and the heater blower out. I was not sure what a plenum chamber looked like but on inspection I found a small metal tube with a flap that was attached to the cowl. Inside of the cowl ( i think that is what is between the windshield and the engine) there was water still there and this drained out of the 'plenum chamber'.

However even before this problem I noticed that my heater is not pwoerful enough and that there is not enought force coming through the heater vents. I also notice a slight sqeaky noise coming from the heatr blower area. I hope that this is the problem as opposed to the heatre uniot itself as I have read that this is quite a big job to remove.
Any ideas?

Ta

 

Plenum Chamber is the space between the screen and the engine firewall that acts as an air collecting box for the heater. You seem to call it the cowl.
The blocked drain explains the water in the heater motor.
The water may have damaged the motor which would explain why there is little air coming thru the vents.
Stuart

 

Ok that helps,

but what do I change the heater blower motor, the resistor pack or both?

 

WITH THE SELECTOR SET TO FULL SPEED WHAT VOLTAGE IS THERE ACROSS THE MOTOR. BATTERY VOLTAGE (12V) OR SOMETHING LESS THAN BATTERY.
Sorry about the caps!
Stuart

 

Stuart,

Got the concept but not sure how to test for that, that is measure the voltage of the motor...where exactly on the blower motor?

 

The blower motor should have 2 wires going to it. (Ground and Supply). If so you just need to measure across these when the motor is running at full speed.
Stuart