What is it and when do you need one? I assume it just serves as some "extra capacitor capacity" to make it easier on the compressor in start-up?? If so - wouldn't you always wants one (except for the extra few dollars it costs)? Thanks!

First, I am a DIY housewife who tries to keep things maintained with minimal knowlege of how things work and what they are called. Hubby is not mechanical, but we try to fix what we can. He likes to call in the professionals, while I am more likely to read forums and try to figure things out first. I am having small water leak - maybe a few ounces a day - that acumulates right next to my ac/furnace unit which is in my laundry room. I am not very familiar with the name of things, but have learned quite a bit by reading old posts. I am trying to do any maintenance possible before calling the hvac people. Expensive!! So, please bear with me. The furnace was replaced in 2001 and the ac replaced in 1998. The house is about 30 years old. OK - the whole hvac thing is a silver box on the concrete floor. At the bottom is a sealed silver box (evaporative coil??)..... on top of that is what I think is the furnace with a vented cover and where the flames are in the winter. Above that is another silver box where a slot is cut for the filters and the air comes down from the ceiling. This top box has a whole house humidifier installed on the side - used only in the winter. Our air and heat comes from the same ducts which are located on the floor throughout the house. Big ducts run from the top part to the floor. There is a summer/winter lever on this big duct and is maybe some sort of bypass? I can hear something inside moving when I change the lever but nothing really sounds different from summer to winter and it seems that cold air is in there. The leak accumates at the base of the whole silver box thing. There are two copper looking pipes that come from the base of the bottom box. One is big and is covered with a foamy padding. It is icy cold. The smaller pipe has a lemon sized thing about half way between the silver and the floor. Do not know what this is, but the leak is right under it. I never see water on it though, so it seems the water is from the bigger pipe. Also at the base of the unit is a hole that looks like a drain. Nothing comes from this and it just opens to the room. I have followed several suggestions that I read here from other threads: (1) The bypass switch on the duct is set to SUMMER. (2) The water to the humidifier is turned OFF. I found it was still turned on. (3) The air filter is clean and new. (4) Outside, water drips freely from a drain coming from the house. It is tilted at an angle and seems to drain by gravity. I asked my husband to suction this drain out with a shop vac. It sucked out about a half gallon of water and I could hear gurgling inside the house when he did this - at the area of those two pipes that are near the floor inside. (5) The outside unit (condenser??) is clean and free of any grass or weeds. Sooooo....is there anything else we can try?? Should the outside drain be dripping when the ac runs? Hubby thinks the ground seems wetter than usual, but it has also been pretty hot. The weather here in Ohio has been pretty hot lately, so the ac runs quite a bit more than usual. The house is nice and cool, very cold air from the vents. The only problem we have is that water on the floor. In several days, it builds up in the laundry room floor and starts to run into the hall and near the house carpeting. Should I open the humidifier and see if it looks plugged or anything? I don't think it even does anything in the summer. It has a plastic drain hose that runs to a floor drain a few feet away. That bottom silver box is all sealed and nothing for me to clean or look at. Those pipes that come ot from it near the floor - what are they for? What is that lemon-sixed unit that is on the smaller pipe?? Thanks for any suggestions!!