I have arcoaire thermostat (not digital) with Comfort Air FBA series system, vintage 1998. The bottom of thermostat has selections: ''EM Heat'' ''Heat'' ''Air'' ''Off''. I am not original owner. Q. Should i slide the selector to the EM Heat Position? The heat condensor has been running outside for some time, with snow around it and making a loud noise with fan. or is this normal?

Flapper door inside duct work most likely stuck open not allowing heat to come thru the heater core.

Hi,
There is ice built up on the fan blades and they are out of balance so they do not move any air....you will need to melt the ice off of the fan for it to work...
The "EM Heat" is to bring on the electric backup heat coils if you have them... you could use that temp. but it will cost you more $$

heatman101

Most thermostats are programed to turn EM heat on when the room temp and the selected temp is two or more than two degrees different. It seems that this is the way yours is working.

That The electric heaters ONLY are being used not the compressor.

It's with discharge pipe line(near to compressor)

If you have heat and air there needs to be 5 wires inside the thermostat, heat pump will need six. If you have heat only there will need to be three wires. If not, the new thermostat will only operate on batteries. Pay close attention to which wires go where and make them correspond on the new thermostat. Also remember mercury is a hazards waste product. Please recycle responsibly.

Check the O/B setting on the thermostat and equipment to insure the reversing valve is energized during the proper heat/ cool cycle. Also check the thermostat wireing to insure electric heat element is set up.

If you have a Gas furnace in the Attic then the answer is yes. The outside condenser will not run if in fact you have a gas furnace.

The blower motor kicks on when there has been a 24 volt control failure.

This usually means that a limit switch has tripped.

Most likely that would be a high temp limit switch or a rollout switch.

First, make sure the filters are clean. and the evap coil is clean. If eaither are dirty/clogged, it will partially block airflow, causing the furnace to overheat, causing the high temp limit to trip.

A rollout switch typically trips for three reasons.
1 flame rollout into the burner compartment due to poor airflow.
2 overheating af teh metal plate the rollout is mounted to, due to dirty, old, rusted components.
3 a bad limit switch.

If your unit has an LED light, count the flashes and it will hepl popint out the problem.
(locate the wiring diagram/flash code list, and correspond the flash count, with the code.)

First, check filters.

yes, replacing the thermostat is definately the first thing i would do