We have a portable air conditioner that we used pretty heavily over the weekend. When I woke up this morning, it has leaked water all over the living room floor. Any ideas of why? Thanks!
...because you didn't empty its drain bucket/tank? Lacking the usual "outside part" where window air conditioners drip condensate, portables usually have a bucket or tank like a dehumidifier that you need to empty. It might have a float that is supposed to stop operation when it's full - like dehumidifiers, that float mechanism may not be completely reliable (if there is one.)
There could be a couple of reasons why it leaked. As Ecnerwal mentioned, it could be the fill bucket float level not working/stuck. But it also be the lower basins float switch stuck (activates a pump to move water from the base of the unit to the fill bucket). If the unit was not level, it could overflow the lower basin before the pump is activated. Also some units can have a drain line attached and if the plug/cap where it goes is removed it will leak from there. Or it could have a rust hole in the lower basin.
Just somethings that come to mind on where water could be leaking from. Most likely you will need to remove the cover and inspect.
WARNING! I've had 6 of these over the years, of various makes. Every one of them will flood the floor when the temperature and humidity are both high. It isn't uncommon here to have 90 F with 98% humidity. I went on a weeklong business trip and when I returned the water was dripping from the ceiling of the room underneath the air conditioner, causing major damage to the rug and floor of the upstairs bedroom and the ceiling of the room under it. In humid conditions there is no way any little condensate pan inside the unit is going to handle the amount of water produced. I now run these sitting on top of stacked pieces of 2 x 4 inside a large plastic tray (called a sweater box & intended for storage under the bed). This week was high temp/high humidity and I bailed out 3 gallons of water from this pan in 24 hours. As far as cooling, these work good for me, but don't ever trust one that isn't sitting over a large catch pan if you live in an area of high humidity.
If your system is leaking water, then first check if the leak is coming from the top vent. Also, verify the rubber plug and drain cap are sealed properly. If the drain cap is wet it means it is not properly attached. Another option which you can try is to Install a drain hose. For this, remove the drain cap and the rubber plug from the back of the unit. Purchase and install the drain hose on the back of the unit. After doing all this, if the unit still continues to leak, then the unit requires a professional repair for this call a professional technician.
Every 'portable' AC unit I've ever seen has a bung plug at the bottom to empty what is essentially a drip tray where condensation accumulates. Depending on where you live, you may never need to empty it as the water will tend to dry up by itself when the unit is off. Elsewhere, water will overwelm the container and end up on your floor unless you empty it regularly. The bung has a cap that unscrews counter-clockwise and then you pull out the plug inside to drain the container; be sure and have some kind of flat pan ready underneath to catch the potential waterfall!
The upright A/C's have a pan in the bottom, which fills up with condensate water. There is a float that is supposed to tell the unit to shut off when it's full.
This pan also collects grime and dust, which can plug portions of the pan so the water does not collect at the float, nor will the water make it to the drain hole.
Unplug and open the unit, and clean out the pan. Many models have a complicated system of ways and channels in the pan, so portions of it can be hard to get to.
If your drain plug is close to the floor, here's a low tech solution that doesn't involve siphoning! Get yourself a set of bed risers, which you can find just about anywhere. Place your portable AC on the bed risers (the casters on mine fit perfectly inside!). Then, connect a piece of hose to the AC's drain using a clamp to ensure a snug fit. Place a bucket on the ground, or on a plastic lid that has a lip to catch a small amount of overflow. The hose will drain into the bucket using gravity! I use a one gallon bucket underneath, and in humid weather, I do have to drain it daily. When doing so, the plug that was used in the drain can be used to plug the hose temporarily to avoid leakage.