Chosen Solution
I have a 2005 Echo and water is coming out of the heater unit at the rear footwell. It is rain water which must getting in from the front of the car under the windshield. We live in a very wet part of the world. Why is water getting in to the heating system and how do I stop it. There is no way it is the air conditioning system, I you lived here you wound understand why we do not have it on in the winter and there is no smell of antifreeze.
If as you say it is coming out of the heater vents and only in the back, then I doubt it would be rainwater. It could be that the heater is leaking internally and it is only a slow drip. Such then when you park up overnight enough runs down through the heater ducts and in to the back. Or because it rains so much you must use your windscreen demister which is actually your A/C. If your drain plug/hose is plugged up it will overflow and run back through the system on the path of least resistance and make its way in to the back. Under the car, near the firewall/bulkhead, where the transmission and engine connect you should see a rubber bung hose. It should be unclogged and free of debris. If it isn’t clean it out. Your mystery water problem may just resolve itself. If it were rain, it would not just leak in to that part of the system.
