Air Conditioning - Central AC unit (Carrier) cools only at night

I must admit that I know absolutely nothing about air conditioners and how they work, so I'll try to describe my problem the best I can.

The outside temperature in recent days has registered between 90 and 100 degrees. Early in the afternoon I've begun to notice that the house has become quite warm even though the central A/C fan is set to Auto and the system is set to Cool, with the temperature set in the low 70s. Today I noticed that at about 5:30 P.M. the unit appeared to begin working properly as the room temperature began to drop. Last night my bedroom became so cool -- cold, actually -- that I was unable to sleep, so I got up and raised the thermostat level. However, earlier yesterday the interior of the house became uncomfortably warm, the same as it did earlier today. In fact, this problem has persisted for several days now.

I can't understand why the unit doesn't function properly during the day, but works extremely well at night. During the day I have lowered the thermostat level to 60 and even down to 40 on one occasion, but doing so didn't appear to make any difference -- at least not immediately.

On the back of the house close to the A/C unit are two white drain pipes and one dark drain pipe. The fan was spinning rapidly on the unit, but I didn't notice any water dripping from the pipes. Shouldn't I notice dripping water when the fan is running? Also, I went into the attic and noticed that the large metal plan underneath the attic unit is holding about one-half inch of water. Is it normal for this level of water to be standing in the pan? I believe the depth of the pan is somewhat less than two inches, so there doesn't seem to be any imminent danger of overflow. However, as I mentioned earlier, I have no knowledge of A/C units and how they work.

I hope I've described my problem in sufficient detail so that someone might possibly have an answer for me. Thank you very much.

Why water in the over flow pan------coil not clean ??? filter not clean?? blower not clean. Then low freon and the coil ice or frost up . check the out side unit where the lines go in . The big copper one cold and wet the small one warm to hot. check and make sure the condensate drain line is clean and clear. Yes the line from the unit should drain. You should have no water in the pan under the unit;)

Thank you for your reply.

Outside, the large copper tube was not cold and the small one was not warm to hot. Both seemed to be about normal air temperature.

What should I do to ensure that the condensate drain line is clean and clear?

I'm wondering if I should attempt to determine what the problem is, or if I should have a repairman come to check. Perhaps if I knew how to check the coil, filter, and blower, then I'd be able to solve the problem myself.

Thanks again.

How long have you lived in this house ? It almost sounds like the utility company may have control of the compressor during peak times.

I've lived in the house for over eight years. It was a new house when I moved in in early 1999.