I don't get any air movement through either the heater/defroster

You may have a problem with the blend door motors on the side of the heater box. As one other person said: "Look at the controls right above the driver's feet area toward the heater box". If they are moving properly all the way, when you move the selectors on the dash, then there may be a problem inside the heater box. If they don't move all the way, then the blend door motors may be bad or binding. Another common problem on these is the control head on the dash not working properly. The control head can be diagnosed with a scanner that can read codes for it. Hope this helps out.

It sounds like vacuum is not getting to the vent, heat and A/C controls. Find the vacuum can. It may be under the hood on one of the inner fenders. The "one-way" check valve is usually located in the line and close to the can, make sure it works properly. The valve could be the very thing that's causing the problem. Trace the lines back to the vacuum block at the intake manifold or fire-wall, and also back to where the line goes thru the fire-wall. Check the can for leaks or obvious holes. They used to be just a plain metal can, but it could be a plastic ball. Check the lines as you go, for breaks and rub-thru's. Move the controls thru all settings and listen for vent door movement. Worst case is a bad vacuum motor or air flow position selector switch, and/or a faulty Blend Door Actuator. If you have been driving around with the Temperature knob or control set at the same spot for months, move it from fully cold to fully hot several times and wait for the air temperature to change each time. This will help reset the blend door and vacuum control system. Hope this helps... Let me know what you find.

It sounds like vacuum is not getting to the vent, heat and A/C controls. Find the vacuum can. It may be under the hood on one of the inner fenders. The "one-way" check valve is usually located in the line and close to the can, make sure it works properly. The valve could be the very thing that's causing the problem. Trace the lines back to the vacuum block at the intake manifold or fire-wall, and also back to where the line goes thru the fire-wall. Check the can for leaks or obvious holes. They used to be just a plain metal can, but it could be a plastic ball. Check the lines as you go, for breaks and rub-thru's. Move the controls thru all settings and listen for vent door movement. Worst case is a bad vacuum motor or air flow position selector switch, and/or a faulty Blend Door Actuator. If you have been driving around with the Temperature knob or control set at the same spot for months, move it from fully cold to fully hot several times and wait for the air temperature to change each time. This will help reset the blend door and vacuum control system. Hope this helps... Let me know what you find.

It sounds like vacuum is not getting to the vent, heat and A/C controls. Find the vacuum can. It may be under the hood on one of the inner fenders. The "one-way" check valve is usually located in the line and close to the can, make sure it works properly. The valve could be the very thing that's causing the problem. Trace the lines back to the vacuum block at the intake manifold or fire-wall, and also back to where the line goes thru the fire-wall. Check the can for leaks or obvious holes. They used to be just a plain metal can, but it could be a plastic ball. Check the lines as you go, for breaks and rub-thru's. Move the controls thru all settings and listen for vent door movement. Worst case is a bad vacuum motor or air flow position selector switch. If you have been driving around with the Temperature knob or control set at the same spot for months, move it from fully cold to fully hot several times and wait for the air temperature to change each time. This will help reset the blend door and vacuum control system. Hope this helps... Let me know what you find.

Here is the info. I hope the pictures show up. please rate assistance. thx.

Air distribution within the vehicle is determined by the function selector switch position. Two airflow mode doors are used to direct airflow within the heater core and evaporator core housing. The function selector switch/cable assembly is used to position these airflow mode doors. Refer to Section 412-00 for description and operation of each of the system functions.
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Function Selector Cable Assembly
The function selector cable assembly moves the airflow mode doors to the desired position using a 2-sided pull-pull type cable assembly. The function selector controls the cable movement. The end of the cable assembly attaches to the airflow mode door/temperature blend door actuating assembly which transfers the cable movement to the 2 airflow mode doors.
An electrical switch is incorporated into the function selector to notify the A/C switch assembly if DEFROST or FLOOR/DEFROST is selected. When DEFROST or FLOOR/DEFROST is selected, the A/C switch assembly will disable the RECIRC request button and send an A/C request to the powertrain control module (PCM) regardless of the A/C request button indicator ON/OFF status.
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SECTION 412-01: Climate Control 2005 Focus Workshop Manual REMOVAL AND INSTALLATION Procedure revision date: 02/25/2004
Function Selector Switch Printable View (173 KB) Removal and Installation

1. Remove the 4 bolts and position aside the lower steering column cover.

1. Remove the function selector knob.

1. Remove the center instrument panel finish panel.
   • Disconnect the cigar lighter electrical connector.

1. Detach the function selector switch.
   1. Disconnect the electrical connector.
   1. Remove the screw and detach the function selector switch.

1. Detach the function selector cable and remove the function selector switch/cable assembly.

1. To install, reverse the removal procedure.

There is a blend door problem.

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HEATING AND AIR CONDITIONING Refer to Section 1 for discharging and charging of the air conditioning system. The heating system provides heating, ventilation and defrosting for the windshield and side windows. The heater core is a heat exchanger supplied with coolant from the engine cooling system. Temperature is controlled by the temperature valve which moves an air door that directs air flow through the heater core for more heat or bypasses the heater core for less heat. Vacuum actuators control the mode doors which direct air flow to the outlet ducts. The mode selector on the control panel directs engine vacuum to the actuators. The position of the mode doors determines whether air flows from the floor, panel, defrost or panel and defrost ducts (bi-level mode).

I have seen this on GM vehicles before. If you take the temp selector and change it to the middle or to cool it will not let warm air go through the defrost vent. The hot air coming out of the defrost vent is because the heater core has warm coolant going through it- and the user generally has warm selected on the temperature setting.

The temp blend door rotates between allowing heat through the heater core, or cold air through the a/cevaporator, or a blending of the 2 by being anywhere between the two.

I would check the heater a/c control head first and hope it's just the control head.
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here is a descripton of the system.

Section 12-03A: Air Conditioning, Heater System, Manual, Ranger and Explorer 1996 Ranger and Explorer Workshop Manual
DESCRIPTION AND OPERATION A/C-Heater System, Manual The manual air conditioning/heater system used in these vehicles is a split-case, blend air design. This design includes the following major components:

• An A/C evaporator housing (19850) which is attached to the engine compartment side of the dash panel (01610). This assembly includes: (1) the A/C evaporator core (19860), (2) the suction accumulator/drier (19C836), (3) the A/C cycling switch (19E561), (4) an internal, A/C evaporator core orifice (19D990) located inside the inlet line to the A/C evaporator core, (5) a blower motor (18527), (6) a blower motor wheel (18504), (7) a heater blower motor switch resistor (18591), and (8) the A/C evaporator case (19897).
• A heater air plenum chamber (18471) which attaches to the passenger compartment side of the dash panel. This assembly includes: (1) the outside/recirculating air inlet door, (2) the panel door, (3) the floor defrost door, (4) the temperature blend door, and (5) the heater core (18476).
• Other components which link and/or control the heating and air conditioning systems include: (1) the A/C control (19980), (2) the ducts and registers, (3) the windshield defroster hose nozzle (18490), (4) the control cables, (5) the vacuum lines, (6) the refrigerant tubes and hoses, (7) the A/C compressor (19703), and (8) the A/C condenser core (19712).

The A/C control (19980) assembly consists of three main parts:

• The function selector knob, a vacuum selector valve combined with an internal electrical switch.
• Heater blower motor switch (18578), an electrical switch that provides four speeds of A/C blower motor operation.
• A temperature control knob, which controls the position of the temperature blend door mounted on A/C evaporator housing (19850) assembly.

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Temperature Control
The temperature selector actuates a variable resistance switch. This switch varies the voltage to an electric actuator used to position the temperature blend door. Positioning the temperature control in any position between COOL and WARM causes the temperature blend door to direct more or less outside air through or around the heater core (18476) for whatever proportion of heated or unheated outside air is desired. The air blends together as it leaves the heater core and enters the heater air plenum chamber (18471) for distribution.
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System Airflow Description Air is drawn into the system by the blower motor (18527) through the outside-recirc. door opening. The air is blown through the A/C evaporator core (19860) and then the heater core (18476) (when the temperature control is moved toward the WARM position). When the temperature blend door is in the maximum COOL position, the air bypasses the heater core. When the temperature control is moved to the right, away from the maximum COOL position, air passes through the heater core where it is warmed, and then mixed with the cool air before it is discharged through the registers. OFF
With the function selector in the OFF position, the outside-recirc. door is in the recirculated air position. It is closed to outside air and no air passes through the system. The blower motor is off. MAX A/C
NOTE: No temperature modulation is possible in the MAX A/C position.

In the MAX A/C position, the outside-recirc. air door is in the recirculated air position. All of the air discharges through the panel registers except for a small amount of floor bleed. The A/C compressor (19703) operates in this function control setting.
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You have to almost remove the dash to get this part out.
Removal

1. Disconnect battery ground cable.
   

1. NOTE: Refer to Section 01-12 for instrument panel removal and installation procedure.
   
   Loosen instrument panel (04320) and pull back from cowl.
   

1. Remove A/C electronic door actuator motor electrical connector from bracket on A/C evaporator housing.
   

1. Remove three A/C electronic door actuator motor retaining screws.
   

1. NOTE: The mounting bracket remains in place on the A/C evaporator housing.
   
   Lift A/C electronic door actuator motor vertically approximately 12mm (1/2 inch) to disengage it from bracket and actuator shaft, then pull A/C electronic door actuator motor back toward passenger compartment.
   

First, feel the heater hoses going into the firewall under the hood. If they are hot, then you have hot engine coolant going into the heater core. If they are not hot, then you either have a bad thermostat or you are very low on engine coolant.

Next you need air flowing through the heater core so it can come out heated through your vents. If the iar is flowing somewhere else, your temp blend door is not moving because the bend door motor is bad or your temp knob on your heater controls is bad. The blend door motor is an electric motor.

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Air Flow Control
Air flow control is accomplished in the following manner:

• Primary control is through the function selector knob , mounted on the heater function selector switch, which is part of the heater control .
• The function selector knob has the following positions: OFF, PANEL, PANEL/FLOOR, FLOOR, FLOOR/DEFROST and DEFROST.
• The heater function selector switch combines a vacuum selector valve with an internal electrical switch.

• The vacuum selector valve directs source vacuum to various vacuum control motors (18A318) . Refer to the System Airflow Schematic and Vacuum Control Charts.
• An internal single-pole electrical switch is also controlled by the selector. The switch controls the electrical supply to the heater blower motor switch (18578) .
• The position of the function selector knob determines the manner in which the system will operate.
• Each position of the function selector knob is detented for positive engagement.

Temperature Control
The temperature control operates in the following manner:

• Temperature control of the heater system is determined by the position of the temperature control knob (between COOL-BLUE and WARM-RED) of the heater control .
• This control knob is connected to a potentiometer mounted in the heater control . This potentiometer is electrically connected to the electric blend door actuator that operates the A/C air temperature control door.

• Movement of the control knob from COOL (Blue) to WARM (Red) causes a corresponding movement on the air temperature control door and determines the temperature that the system will maintain.

System uses a reheat method to provide conditioned air to the passenger compartment.

• All airflow from the blower motor (18527) passes through the A/C evaporator housing .
• Temperature is then regulated by reheating a portion of the air and blending it with the remaining cool air to the desired temperature.
• Temperature blending is varied by the air temperature control door, which regulates the amount of air that flows through and/or around the heater core (18476) , where it is then mixed and distributed.

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inside you plenum box:

If this is the mechanical unit it is possible that the wire in the back has come adrift or the clip that holds the wire in position has come off and now the whole cable is moving.
Have a look at the bottom of the dash where the controls are fitted and move the control at the same time looking if there is any movement below the dash, take it from there