I have a 98 e150 club wagon with heat issues. I have heat going to the back of the cabin but no heat to the front. I have replaced the heater core, thermostat, and the heater by pass valve with no results. I also inspected the heater flap door and actuator and they seem to be working properly. I am at a loss anyone have any suggestions or answers, it would be really appreciated.

 

After running the engine about 5-10 minutes feel the hoses under the hood going to the front heater core and see if both are warm/hot. They should be almost the same temp.
If not , there is a good chance the heater core is full of trapped air. You might need a special tool to release to upper hose at the heater core ,with the engine running,and pull the hose back just enough to let the air out because after that coolant will come rushing out. See if that doesn't correct the problem.

 

Yes I checked to make sure the hoses and they were pretty warm. I also tried by passing my rear heater core to see if that would make any difference but nope it didn't. I also replaced the hot and cold switch that also did not work. Not sure where to go from here.

 

I'm having the same problem with my '99 Windstar. Did you ever find the problem?

The Haynes manual suggests it might be a blocked heater core or hose. Recommendation is to unhook the hoses and back flush the core. I may try that today. There is one fuse that controls the heater blend door but it has other things running off it so I doubt that is going to be the problem. Still worth checking out.