The blower starts before its warm and it blows cold air for about 30 sec when its shutting down .
When any unit 1st come's on, you'll always have some cold air that's in the ducts that will blow out before you get warm air. If your duct work is uninsulated in a cold basement or crawl space then it will be even more noticeable. When the unit is heating from the Heat Pump mode, it takes a little longer for the gases to get warm enough so you'll fell heat. When it gets cold enough for the unit to switch from heat pump to the gas or electric heat source, you'll get warm air faster. If you have gas heat, some Thermostats have an anticipator setting for the gas valve. If it's set wrong it will effect the on/off cycle of the gas valve.
All duct work in non heated and a/c spaces, including inside walls,above dropped ceilings, in attics and crawl spaces, must be sealed & taped at the seams and joints and then insulated and taped.
Most new construction has solved that problem with insulated duct board, flexible insulated supply's and special tape.
on Dec 12, 2013