"Jeff" wrote:

Starting and stopping are not as efficient as running continuously.

While its true that starting a compressor takes more energy than running it,
that surge of extra use only lasts for a second or two. Most residential
compressors are sized to meet the max load and it most definitely costs more to
run them continuously than to run as required.

High efficiency ACs have two small compressors. They run only one unless higher
cooling is required. This is the only time running continuously or near
continuously makes sense, but most people don't have these types of AC.

AC units are designed to run continuously.

Again, we're not talking about whether the compressor can handle it, we're
talking what is the most efficient. See above.

Also the house will gain less heat during the day as it is warmer so you will be removing less total heat.

Excuse me? That statement makes no sense. The issue is cooling loss from inside
the house. As the interior temps rise, there's less cooling loss. By not running
the AC during the day, you aren't losing cool air through windows, doors and
insulation gaps which gets replaced with warm air, which has to be cooled again.

When the house is unoccupied it will have no moisture source vs. when you
are home.

Which has nothing to do with AC efficiency.

For the real scoop from the DOE:

http://www.eere.energy.gov/consumer/.../mytopic=12720