We have relatively new house. The central air was installed in 2001/2002. This is OUR first time using it. First thing I realized was the circuit breaker for the condenser and fan was bad, so I replaced that. The unit ran fine for a few days. Then we shut it off for a few days. When we started it up again a few days later the condenser started, but the fan on top did not run. Thanks to this forum I realized that it was a bad capacitor. I changed that and we were back in business... so I thought!

Now a week later the system just isn't working right. The condenser and fan are turning on, but they seem to be struggling. The house was not cooling down. The basement floor was soaked from the return pipe 'sweating' all over the place, but the house was like a sauna. I shut the unit off.

The next day I turned it back on again and it seemed to be working okay. The house cooled down. It was a struggle and it took a looonnnngggg time, but it did cool down. It never got to that too cold point though. It just knocked the edge off.

What is going on? What am I missing? Any help would be greatly appreciated! Thanks

Condenser coil could be clogged, air filter also. The sweating your talking about, is that the condensate from the evaporator in the plenum? That's normal.

I changed the filter but that didn't seem to help. If the condenser was clogged would it work again the next day?

Check the contactor (relay). They are at the heart of properly maintaining an air conditioner and are overlooked by almost everyone. As they open and close, they become pitted. The effective cross-sectional area of the points becomes less and the resistance goes up by a square function. This results in the compressor starving for current, which can eventually burn it up. Annually, clean the condenser coils by removing the covers on 3 sides of the condenser and gently hosing down the coils to remove debris and dirt; check the condition of the contactor; make sure the start and run condensers are good; and use ISO 32 wt. turbine oil (ACE Hardware) to lubricate both ports on the condenser fan motor with 15 drops of oil. Make sure the start condenser is not leaking acid--they can blow like a firecracker. Turn off thermostat, 220v. Power to the condenser, and 110v. Power to the furnace before checking out the condenser.

From what you described about all of the water on the floor and the unit not working one might but working the next sounds to me like the Evaporator coil about the furnace is dirty or the unit is low on freon. Both of these items will cause the evap coil to start to freeze over and the more it freezes the less air that goes through the coil and therefore it will make more frost to shut down more air. Then once the unit is shut down the ice melts and over loads the capacity of the small drain pan, hence the water all over the floor. The Evap coil can be cleaned but it is not easy for an inexperenced person. The freon levels can only be checked by a person certified to work with freon.

That's a good point: if there is more condensate then normal, it sounds like an iced evaporator. And that would explain why after it sits awhile it works OK, because it defrosts.

That sounds right to me. After looking at it again I realize that the evaporator coil? (is that what is on top of the furnace?? ) has ice around the hole where the large, insulated, sweating pipe is going into it. There is also cold air leaking from around that hole.

Why would that leak cold air? Is there something going on on the other side of that cover?

Thanks for all of your help!