We woke up this morning and the house was pretty cold at 67 degrees, even though the heat was set at 73 degrees and the fan was still running. I currently have a 2 year old home with a Carrier Systems (Fy4ANB060), Compressor (25HBA36019003) and a Honeywell TH6220D programmable thermostat. This is the first issue I have had with the system, so I hope someone can help.

I reset all breakers even though they were not tripped. I removed the digital thermostat and all wires appear to be tight. I checked the control voltage at the thermostat and it is 26.4vac. I also checked the air handler and the voltages appear to be okay with no tripped breakers or blown fuses.

When I press the heat on the thermostat, it acknowledges heat and the "auto mode" comes on and fan starts blowing but there is no heat. I also tried the AC unit and it appears to come on, but the air isn't very cold and it appears the fan is just blowing cool air from the out side. System worked perfect yesterday and we dipped into the low 30's last night, does anyone have any suggestions?
Thanks
Donnie

Also, when turn the heat on the system waits 3-4 minutes and then turns on. When the system finally does come on, "Auxiliary Heat" is also noted in the Honeywell display where it normally just says HEAT or EMERGENCY HEAT.

Hmm... a loss of charge would result in diminished heating capacity, and if no temperature increase was noted in a fixed amount of time, second stage (emergency heat) would most likely kick in. Does the compressor kick on or just the outdoor fan?
Have the charge checked and make sure the compressor isn't locked out. You may need a service call here.

Thank You for the response Missouri Bound! It did not get nearly as cold yesterday and last evening, so we left the heat off all day. We started the heat last evening around 6:00pm and kept it at 72 degrees and it seemed to work okay last evening. The heating system did not kick over to emergency heat or auxiliary heat and everything is working fine on the standard heat setting.

Now I am really puzzled and concerned for our cold snap /freeze?

Could this have been a "charge issue" that became an problem on the previous colder night (mid 20's)? Or, if it was a "charge issue" should I have had problems last evening as well?

If the charge is low the problem will be less noticeable the warmer it is, since you won't need as warm as air to heat the home. But it needs to be addressed anyway. Have a competent HVAC tech put some guages on it and check out the system. Do it now before it gets too cold.

Will do, thank you Missouri Bound!