Blows cold air (by 2 users)

package unit heats the house, then when the thermostat reaches the preset temperature it kicks off. when the temperature drops in the house and the furnace kicks back on -- only cold air blows out -- we have to go outside and pull the disconnect, wait a second or two and then plug it back in. By the time you get back in the house it is blowing warm air again. We have woke up several mornings with the house almost the same temperature as outside. Please Help! April in Weston, WV