I put a new battery in the Maverick and drove it around a while today. It's been raining on and off all day. Well I had the old battery sitting on the passenger side floor and when I picked it up the floor mat was wet. After looking a little closer on that side I found one small half circle crack on the front of my heater box and a much longer one on the bottom. Water was slowly dripping out of the one on the bottom, more so when I'd apply the slightest pressure to it. There was rust on the passenger side floor when I bought it and I guess I know why now. Do I need a new heater box now or can I repair it? Could this have anything to do with why my vacuum controls don't work? And why is it leaking water anyway? It shouldn't have water in it from outside the car right? I drove it as a daily driver for about a year and never noticed it happening then. I guess it's so gradual that I assumed it was water that had been tracked in.
You need to replace the heater core. That is why its leaking. The heater core is inside the heater box.
A cowl leak will cause a rain WATER leak...a leaking heater CORE will cause an antifreeze leak. A plugged A/C drain will cause a condensation leak. I fixed my heater box with epoxy glue and tin flashing.
If the box is cracked and it only leaks when it rains, the hole in the cowl where the air comes in has a 1-1.25" raised portion of metal to divert water around the inlet. If that portion of the cowl is rusted through, it will leak water when it rains.
Check out pic #4. This is what injectedmav is talkin about. http://mmb.maverick.to/showpost.php?p=708858&postcount=104
It is also very humid when it rains, and your evaporator will sweat alot. Does it leak with the A/C off also? If so, then it is probably a leaky cowl hat letting rain water into your box.
A heater box will leak at the seam where to front half meets the back anyway if its getting wet inside the box. A crack housing ain't going to make it leak any faster
