I think our a/c unit is running toomuch. I can see that the outside temprature drops but still my a/c unit keeps running as if it is hot outside.

Lets say if my understanding is right ...

When the outside temprature is 90F i usually set our inside temp at 83f still unit runns every 10 mins.

Unit runs and it keeps house ok but i am worried about power bill.



Where do i start .. are there any diagnostics that i perform to see what is going on.

 

You mean it runs for 10 minutes but then stops, and then starts up again? Generally if the a/c is not putting out enough cold, it just keeps on running.

See if your compressor or fan outside is going into thermal overload, or just plain shutting off, or if your furnace blower motor is. All 3 have to be operating. You could have a bad motor or bearings that are causing heat/stickiness. Or you could have a refrigerant problem and some pressure switch is kicking out the outside unit. Let us know what you find that is stopping. Something is stopping for your unit to be cycling like this.

 

How are the vents in the attic??? Do you have enough. How is the insulation up there got a R38 or better there. Filter clean, outside coil clean??
no bush close or around it so air cant get to it.
Big copper line outside cold and wet small copper line warn to hot ,when running.

ED