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Heater System Ford Explorer I

Heater 3 illustrations ~1023 words

DESCRIPTION

Heater system is a blend-air design consisting of control panel, heater blower assembly and plenum assembly. Heater blower assembly is located in engine compartment, and contains blower motor, fan wheel and blower resistor. The plenum assembly is located in passenger compartment, and contains heater core, floor/defroster door, panel/defrost door and temperature blend door.

TEMPERATURE LEVER

The temperature lever mechanically operates a cable to adjust the temperature blend door. Temperature blend door is in the plenum assembly. When temperature lever is in COOL position, blend-air door closes off airflow to heater core. When lever is in the WARM position, air is directed through the heater core. In intermediate positions, heated air is blended with cooler incoming air to achieve desired temperature.

FUNCTION SELECTOR LEVER

Function selector lever can be placed in OFF, PANEL, PANEL/FLOOR, FLOOR, FLOOR/DEFROST and DEFROST positions. The function selector lever mechanically operates the floor/defroster and panel/floor function doors.

Outside/recirculation door is controlled by a vacuum selector valve and vacuum motor. When function selector lever is in the OFF position, vacuum is applied to outside/recirculation door vacuum motor to close off outside air flow. When function lever is in any other position, no vacuum is applied to outside/recirculation door vacuum motor, and outside air is allowed to enter the vehicle.

BLOWER SPEED SWITCH

Blower speed rotary switch has LO (low), medium-low, medium-high, and HI (high) speed positions. When function selector lever is in the OFF position, the blower speed switch is open.

TEMPERATURE CONTROL CABLE

  1. Slide temperature control lever to its maximum left and right positions. When temperature control levers are moved back and forth firmly, the temperature damper door should be heard seating.
  2. If temperature damper door is not heard seating, squeeze glove box sides together to disengage tabs, and let door hang freely. Working through glove box opening, remove cable housing from metal clip on top of plenum by depressing clip tab, and pull cable away from clip.
  3. Leave core wire end loop attached to temperature control cam on plenum. To adjust temperature control cable, move control lever to COOL position, and ensure it does not move.
  4. Push cable housing (Black) to seat blend door (push until resistance is felt). Install cable housing to clip by pushing it from top until it snaps into place.

FUNCTION CONTROL CABLE

  1. Slide function control lever to its maximum left and right positions. Cable should reach detents on both ends of travel. Ensure proper airflow in each cable position.
  2. To adjust function control cable, move control lever to DEFROST position and hold. Pull on cam jacket until cam travel stops. Reinstall cable housing to clip by pushing it from top until it snaps into place. X1 TROUBLE SHOOTING

BLOWER MOTOR INOPERATIVE

Check fuses. Check heater function selector switch. Check for battery voltage at blower motor. Check for open in blower motor ground circuit.

BLOWER MOTOR ONLY RUNS IN LOW

Check blower motor switch. Check wiring for open circuit. Check ground circuit for open circuit. Check for open blower motor resistor.

BLOWER MOTOR ONLY RUNS IN HIGH

Check for open blower motor resistor. Check for open thermal limiter. Check blower motor switch.

AIRFLOW FROM WRONG OUTLETS

Check for pinched, broken or improperly adjusted cable.

INSUFFICIENT HEAT

Ensure cooling system is operating properly. Check heater system hoses and core for coolant flow. Check for loose or misaligned cable to temperature blend door.

BLOWER MOTOR VOLTAGE TEST

  1. Place temperature selector lever in mid-range position and function control lever in PANEL position. Connect voltmeter probes to connector at rear of blower motor.
  2. With engine running, measure voltage drop across motor. Voltage reading for each blower switch position should be as specified. See «BLOWER MOTOR TEST SPECIFICATIONS»(/ford/explorer/i-1990-1994/remont/heater/#heater-system) table.

BLOWER MOTOR CURRENT DRAW TEST

  1. Disconnect blower motor. Connect ammeter between left (positive) terminal on motor and corresponding terminal of wire harness connector. Connect a jumper wire between right (ground) terminal on blower motor and corresponding terminal of wire harness connector.
  2. Place temperature control lever in mid-range position. Place function control lever in PANEL position. With engine running, record current draw for each blower speed. Current draw (amperage) should be as specified for each blower speed. See «BLOWER MOTOR TEST SPECIFICATIONS»(/ford/explorer/i-1990-1994/remont/heater/#heater-system) table.
Switch PositionVoltsAmperes
Low5.03.5-5.5
Medium-Low8.05.0-7.5
Medium-High10.07.0-9.5
High12.09.5-11.5

BLOWER MOTOR TEST SPECIFICATIONS

Scheme 1

Scheme 1: CONTROL PANEL
Scheme 1: CONTROL PANEL

Scheme 2

Scheme 2
Scheme 2
  1. Disconnect negative battery cable. Remove ashtray, ashtray retainer and illumination bulb. On 4WD vehicles, disconnect 4WD transfer switch wiring from finish panel. On all models, gently pull out finish panel from instrument panel.
  2. Remove 4 screws attaching control panel assembly to instrument cluster. Pull control panel assembly through instrument panel assembly. Remove electrical connections from blower switch and illumination light.
  3. Remove vacuum hose harness connector from vacuum switch on control panel. (Scheme 1) Release temperature and function cable snap-in flags from White control bracket.
  4. Remove temperature control cable (Black cable with Blue snap-in flag) from control panel by rotating cable until "T" pin releases cable. Pull enough cable through instrument panel until function cable (White cable with Black snap-in flag) can be held vertical to control panel.
  5. Remove control cable from function lever. Remove control panel assembly from instrument panel. To install, reverse removal procedure.

PLENUM ASSEMBLY

  1. Disconnect negative battery cable. Loosen instrument panel attaching bolts, and pull panel back for access to plenum assembly. Remove heater hoses from heater core, and plug hoses. (Scheme 2)
  2. Remove blower motor assembly. See «BLOWER MOTOR ASSEMBLY»(/ford/explorer/i-1990-1994/remont/heater/#heater-system__blower-motor-assembly) below. Remove 2 nuts from plenum studs at firewall in engine compartment. Pull plenum away from firewall, and remove plenum assembly. To install, reverse removal procedure.

BLOWER MOTOR ASSEMBLY

  1. Disconnect negative battery cable. Remove air cleaner. Disconnect wire harness connector from blower motor. Disconnect blower motor cooling tube at blower motor.
  2. Remove 3 screws attaching blower motor assembly. Hold cooling tube aside. Remove blower motor assembly from vehicle. To install, reverse removal procedure.

HEATER CORE

  1. Drain coolant from radiator. Disconnect heater hoses from heater core, and plug openings. (Scheme 2) In passenger compartment, remove 4 screws from heater core access cover on plenum assembly.
  2. Remove access cover. Pull heater core rearward and down while removing it from plenum. To install, reverse removal procedure.
Fig. 3: Heater System Wiring Diagram (Explorer & Ranger)
Scheme 3: Heater System Wiring Diagram (Explorer & Ranger)