On 7/28/2011 1:45 PM, kansascats wrote:
On Jul 13, 7:26 am, wrote:
On Jul 13, 8:16 am, "Jon Danniken"

wrote:
kansascats wrote:

We are around 97F outside now -- cooling to 78F inside.

Sounds like your A/C unit is too small for the area you are trying to cool.
It shouldn't have to run constantly in order to keep the cooled area at 72.

Jon

A properly sized ac will run pretty much continuously when the temp is
in the high 90s. A larger unit would not run enough during more
moderate outdoor temps resulting in high indoor humidity making it
feel clammy. You want a unit that is just big enough to hande the
area but not bigger. It's perfectly normal to size one such that it
can't keep up when the outdoor temp is unusually high. And the wear
on them is actually less if they run for longer periods rather than
startng and stopping a lot. Startup is hard on the compressors
because they start in a loaded condition, the refrigerant is already
near or above 100 psi when not running.

Insightful reply - thank you. I never thought much about that. Many
talk about being able to cool-down a room quickly, but the logic you
supplied makes sense. Our house central AC does nearly run all the
time when it's in the upper 90s. In fact on some days when the wife
is cooking the temp is a few degrees about the desired temp -- it just
cannot keep up. I replaced the fillter just to be sure, but I think
it's just at it's max for the above average outdoor temp.
And, yes it IS normal for the power to change with temperature. Also,
that's what nice about the new 2 stage AC units. I have a 2 stage
central unit and as the temperature doesn't usually get real high at
2500' up in the mountains, it usually only runs on stage 1. So it runs
longer and takes out more humidity. I also have a Honeywell thermostat
that will over run the AC in order to reach a settable humidity level.
It works extremely well. The only time I have seen it go into stage 2
is when you manually set the thermostat to a lower value or the
thermostat changes the temperature due to the program.