Heat Pumps and Electric Heating - Heat pump not working - Grandma needs help!

My daughter has a 2 year old Braeburn 1200 heatpump. Today only the aux heat will run. I do not know anything about heatpumps. It got down to about outside 30 last night and she had her heat on and it worked fine when she went to bed. This morning, the house interior temp was 66, the thermostate was set for 72. This has been going on now for about 5 hours, with only the aux on working. Any suggestions?

Now the aux heat is off, and just cold air is blowing. Help?

is actually outside in the yard...it looks like an air conditioner. The fan on top of it should be spinning and the coil should be frosting, but not a big chunk of ice. If you see the fan stop and the AUX on...this is normal and a defrost cycle.During this cycle the outdoor unit will stop the fan and the air conditioner/heat pump will cool the inside coil, heat/melt the outside coil, this is why the aux coil is on because of the cool coil. The aux is trying to offset the cold coil during the defrost cycle. If while this is happening, THE AUX LIGHT IS ON, and cold air is comming, then I suspect the heating elements inside the air handler have failed. First check for a tripped breaker in the fuse box.

Thanks. I checked the breaker box in the house, no tripped breakers. No heat again this morning, so I'll call the repair guys. Thanks so much for your response. I appreciate it. Grandma

Air conditioning tech found that the thermostat had failed, was actually cooling instead of heating - weird. Replace 'stat and all's great - kids are warm! Thanks for your help!