No heat from heat pump

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.

could be as simple as anits in the
cut off switch.

Are you using a "very powerful" AC to cool off a relatively small space? The AC has a thermostat, if the return air is meeting set point, the compressor would stop. The fan could still be circulating, hence the perception of warm air. What you should do is don't block the ventilation, and direct the cold air toward the ceiling. The cold air will sink (due to higher density) and create better circulation and temperature mixing.

Will run with defrost or blend selected on the heat control,to help dry the air,shoudn't run when floor heat is selected.

R-410A is a type of refrigerant and not a capacity rating of an air conditoner. 12,000 Btu's equals a 1 Ton of cooling capacity.

I'm going to assume that you know that heat pumps do not put out very warm air just lots of it. If you know the difference then I would say that your auxillary heat system has a problem. You could have electric or gas. You did not mention this piece of information. Give me more detail about the problem and I may be able to help you.

hardrocko

could be low on freon and the heating element limit switch could be bad, if it has one

It seems the automatic idling lifter (sensor) once you switch on the a AC system has failed and thus at low idling the Ac compressor clutch gives in stopping the compressor to spin.
You have to check tht system out.
Hope this helps!

you can try recharging the system...it's a fairly simple process and freon can be purchased at any parts store. here is an overview:
http://www.aa1car.com/library/ac_recharging.htm

if you are desiring to have it 62 degrees in the house, the cool setting needs to be more to like 66 deg and the heat setting needs to be like 58 degrees. that would make it more around 62 degrees in the house.

change the heat setting first to 58 and then change the cool setting to 66. this gives your temperature 62 +/- 4 deg.