Outdoor air conditioning units are often out of sight, and therefore out of mind. But should you happen to be outside walking around and notice water or liquid around the base of your outdoor AC unit, this should set off some alarm bells in your brain. Don't listen to those bells too carefully just yet — there's a chance nothing at all is the matter. But there is also a chance something is wrong with your air conditioner. Here are a few possible places that liquid could be coming from, along with some tips to help you figure out the source of the moisture in your case.
First, try to deduce the color of the liquid. This can be harder than it seems since often, the liquid will mix with dirt on the ground around the air conditioner after it trickles down. An easy way to tell is to dip a piece of white paper in the liquid. If the liquid is any color other than clear (or slightly brown from mixing with some dirt), then the liquid is refrigerant, not water.
It's most common for AC refrigerant to be pink these days, as that is the color put into R-401a, the most common modern refrigerant. If you have an older AC unit, your refrigerant might be green — that's R-21.
Refrigerant leaks can not only pollute the soil, but they make your AC unit quite inefficient. You'll want to call an HVAC contractor to fix the leak and add refrigerant to your system. If you do have a really old AC unit that runs R-21, they might just suggest getting a new air conditioner since R-21 has been phased out and is nearly impossible to purchase now.
If the moisture is clear, then it is probably just dripping from the coils as they get chilly while the AC works. This is normal. You'll notice more condensation on days when it is really humid because the moisture won't evaporate as quickly. This could be why you're just starting to notice the drops of moisture now after the area was dry in previous weeks. If you are noticing outright puddles of moisture, you should change the air filter and wash the coils. This will encourage air to pass through the system more quickly, which should keep the coils from getting so cold, which should reduce the amount of condensation produced.
There's a big difference between a sweating air conditioner and one that is leaking refrigerant. If you notice moisture around your air conditioner, be sure to identify it.