View into the top part of the engine bay, from front to rear. The rusty surface in the centre is where the heater unit was taken out. The two square "funnel like" holes going down bring the hot air into the driver's compartment (ending under the dashboard). The ventilation flap in front of the window has been removed. Cold air enters there and is guided into the heater unit via the vertical open slit. Barely visible is a recess in the center of the rusty patch to collect the rain water that entered via the ventilation flap and has trickled down through the heater unit. From that recess, the water goes to the round hole visible above the gear box opening, and from there down onto the street. The rain water has caused all that rust; the bottom of the heater unit will be equally rusty.