Since I had my home air handler replaced, the system runs much longer than it used to before my old unit was replaced. It sometimes runs for hours before cutting off to cool or heat 2-3 degrees. The old unit worked much better. I called the company that installed it and they say it is all OK. I think it is undersized or the unit just isn't cutting it.

I have a Trane system and feel there is NO WAY this unit should continue to run and run and run. The air flow from the vents into the rooms on the house seems really weak. However, the company who installed it says everything is good. I also had an alternate A/C company check it and they didn't have a real explanation.

What can I do to pinpoint the problem? How are air handling units sized?

Thanks -- I would like to hear that damn unit go off every once in a while!

Brand of outside unit.
Exact model number of outside unit if heat pump equipped.

Brand of new inside air handler.
Exact model number of inside unit.

Brand of old air handler.
Exact model number of old air handler.