I have an older york heatpump,
Problem is sometimes, when heat is on thermostat will kick off,
Fan will keep blowing, but cold air comes out.
Thermostat emergency heat light flashes 4 times then pause then 4 times etc.
Only way to fix is trun to E heat, or turn off heatpump a few times,
Sometimes it will work correct for days other times only about 1/2hr.
Always does the 4 time flashing of E light when it messes up
