Your problem sounds like the common blend door problem on the Ford Expeditions, and Ford Explorer.
Check related link below
how is it my heater control on my ford fiesta flight 1998 only works on no. 4
you will have coolant in your passenger front floorboard and when you turn your heater on your windshield will fog up
Remove the wiring harness from the back of your 1998 Chevy Lumina heater motor. Remove the heater motor retaining bolts. Remove the fan from the front of the heater motor. Reverse the process to install the new heater.
replace the BLOWER MOTOR RESISTER....YOU CAN FIND IT INSIDE THE CAR UNDER THE PASSENGER SIDE FRONT DASHBOARD.
The block heater plug in on a 1998 Ford Windstar is in the engine compartment on the passenger side of the vehicle. When lifting up the hood, look on the left for a small hose that is coiled up at the very front, above the passenger headlamp. The block heater itself is plugged into the front of the motor on the passenger side.
did the heater core start leaking? anyway you should have no problem with the air if you bypass the heater core.
The dash has to be removed. Once the dash is out, the top of the heater case comes off to gain access to the core.
In Subarus the temp control for the heater does not control the coolant flow, just airflow past the heater core. If you get no heat, there is no coolant in the heater core -- either there is no coolant or it is not circulating.
Does your blower motor work? If it does and there is no heat the blend door actuator is probably not working and is not letting warm air into the vehicle. The blend door is staying in the cold position.
How do you replace a heater core in a 1998 Ford Expedition?"
It is your blower motor resistor. It is about a $20 part and you can put it in yourself if you are handy. If not, a mechanic will put it in for $25-$50. I have had this happen several times to my stratus.
How do I replace the block heater in my 1998 F150 4.6L?