I had a rather unusual problem with my central heating and air conditioning system recently.
There was leaking going on outside on the heat and a/c unit itself.
At first I thought it was some kind of water. But then I found out that it was actually a freon leak. This was caused by who knows what, but I had to call the local heating and air conditioning company right away. They then sent out a certified heating and cooling specialist to assess the issue. They figured out where the leak was coming from and were able to patch it up pretty fast. They also while they were here gave my central heating and air conditioning system an HVAC tune up as well as check up. Other than the freon leak, everything else seemed good to go with my central heating and air conditioning system. I had not had a tune up on my central heating and cooling unit in ages, so it was a good thing I finally did. They say that HVAC tune ups and check ups are the way to keep your central heating and air conditioning system alive longer. And probably had i got an HVAC tune up and check up on my central heating and air conditioning system, this leak may not have ever happened. Most likely the certified heating and cooling specialist would have found the beginning of the leak and fixed it before it actually became a major issue like it was at this very moment in time.