No rear heat on 99 expedition.

I've got no rear heat on my 99 expedition. I took apart the a/c heater unit and noticed that the A/C condenser stays cold all the time. I monitored the the temperature of the a/c condenser with a temp gun and noticed that as soon as I turn the rear air the condenser starts to get cold. The blower fan blows air through the a/c condenser and then the heater core warms the cold air to just warm. So I guess my problem is from my condesnser not shutting down. What keeps the freon from cirulating through the condenser. Anyone have any ideas.

Does the blend door actuator work properly? That is what determines the temperature of the air coming into the vehicle.

Yes it does. I checked it. Is there a sensor that monitors the temperature. If there is what would it look like.