If by "exterior overflow drain" you mean a pan external to the AC coil and ducting (often installed on a horizontal attic crawlspace unit), and if there's water filling that "exterior overflow drain," then it would be likely that the coil's own drain pan has formed a leak. If the evaporator coil is older than 10 years, it probably was made of sheet metal rather than plastic, and so it may have rusted through in a location not readily visible.
It has to drain the condensate buildup somewhere... Some drain directly into the homes plumbing and only drain outside the home when the inside line has plugged up, like an overflow pipe.
When air is cooled the water in it comes out (like mist forming on the outside of a class filled with cold coke) and this happens in the air conditioner. Normally the dripping water is drained way to the outside (or a drain) by a pipe. If the pipe gets blocked the water will overflow and the conditioner will leak water - get it serviced.
The overflow tube is clogged is my first guess, unless someone or something has cracked the drain tube with activity in the area.
The overflow is built into the sink, it is not part of the drain. If there is no overflow, you can not add it.
AIR CONDITIONERS ARE SUPPOSED TO LEAK. ALL YOU CAN DO IS ATTACH A HOSE TO THE DRAIN AND RUN THE HOSE SOMEWHERE WHERE IT CAN SAFLEY DRAIN.
It kills the bacteria slime that clogs the overflow pipe. If the pipe clogs up the water fills up the drain pain. when it reaches a certain level it shuts the air conditioning down.
If you have been running your air conditioner, it's possible that your drain hose is clogged, and the condensation is dripping in. It is also possible that you have a leak in the heater core or a windshield leak.
The air conditioner does not have a drain. I dont think an air conditioner has a drain
Most of the one's I have run across do not have an overflow. Mainly used for disposal, dumping out drinks, etc, not for washing so overflow not really an issue. Also, most are stainless which do not lend themselves to an overflow drain.
Usually. Going through the overflow drain gets you straight into the drain without having to make the sharp bend in the tub drain. There could be a trap that comes apart in the drain underneath if it is accessible.
In my experience, I would say no. Several reasons can prevent the overflow from working. Since the overflow of the sink is rarely used it has a tendency to be blocked at the lower portion where the sink joins the drain pipe. During normal use and over years the holes in the sink drain at the point where the overflow and drain pipe meets has a tendency to clog making the overflow drain slowly. You can notice this when your sink drains with a "gulping" sound. You can test the overflow drain and see how obstructed it is, but do it slowly and do not turn on the faucets on full.
Yes, the gasket between the overflow pipe and the tub can go bad, or it can leak around where the pipe is attached to the drain.