A bad terminator thermostat will NOT allow the heater to come on. I have never seen one fail to open however. I have seen a dummy bypass one and it was not pretty. The way it works is this: The timer shuts down the compressor and kicks in the heater. For 21 minutes. If that heater was to stay on for 21 minutes it would most likely burn down the house. So they install a termination thermostat in series with the heater to kill the heater when the temperature gets 50 degrees F inside the evaporator housing. This is enough to melt the frost on the coils. If the drain is open then the water will simply go into a pan located on the bottom of the ice box. If that drain is stopped up the water will cascade down the rear wall of the fresh food compartment and puddle up under the crispers on the floorboard of the ice box.