A winter or two back, our 122S developed a bad leak in the rain. The carpet would get completely soaked, and the source of the water was a complete mystery. All seals seemed to be in good shape, and nothing above the floor would get wet.

As we rely on this car for our transportation, there was not much we could do about it except mop up the water as much as possible (an old chamois does a pretty good job) and hope for an early spring. Unfortunately, that particular winter seemed determined to make up for the previous six years of southern California drought all by itself, so a certain amount of urgency attached itself to finding a solution.

With all that humidity in the car, the windows would fog up almost immediately. Oddly, the defroster had little or no effect in clearing up the mist -- there were times when it actually seemed to make matters worse. The only way to drive the car was to arm the passenger with towels with which to continually wipe the inside of the windshield, and never mind about seeing out the back window. This was more than inconvenient -- it was positively hazardous, and completely unacceptable.

Eventually, the answer came to us. There's a drain pipe in the air vent in front of the windshield. Over the course of the previous several years, this pipe had become pretty well plugged with old leaves and pine needles. This had allowed what little water we'd had fall during the drought to seep out with no problems (and I had learned not to spray water directly into the vent when washing the car). However, dirt and sand blown into the vent could not pass, and had finally calcified and plugged the top of the drain hole completely water-tight -- we couldn't even tell where the hole was just be looking at it.

Rain water now had nowhere else to go but directly into the heater box, eventually running out the bottom onto our carpet. No wonder the defroster was just making the steambath worse!

Of course, the fix is easy: clean out the drain. The easiest access is by removing the blower motor from the front of the box (you might be surprised by how much stuff you'll find lying around on top of the heater core, while you're in there). Remove the rubber drain tube and blow it out. Poke any crust out of the drain hole. Reassemble.

This operates very similarly in the 544, 122 and 1800 cars.