Nissan 240sx S13 Heater System: blower motor, heater valve, ventilations and more

1989-1994 Nissan 240sx S13

HEATER

The heater assembly is contained in a housing beneath instrument panel or gauge cluster. Heater assembly consists of blower motor, heater housing and core, heater valve, and control panel.

VENTILATION

Ventilation is a separate function from heating and is combined with the heating unit to obtain fresh air ventilation when required. Separate selector lever, push button or position setting on mode lever permits fresh air to enter passenger compartment. Blower switch position determines airflow volume.

OPERATION - MODE SELECTION

Mode lever or push button controls airflow doors (intake, blend-air, heat, defrost and ventilation). Lever setting on control panel determines door positions.

Fresh/Recirculated Air Door

With door in the open position, outside air flows into heater system after passing through blower motor fan. With door in closed position, inside air is recirculated through heater system.

Ventilation Door

Ventilation door (fresh vent door on some models) permits fresh air to flow from dash panel registers.

Defrost Door

Controls air delivery or defroster outlets when this mode is selected. This separate door opens when mode door closes off floor and dash panel outlets to direct air to windshield.

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TEMPERATURE LEVER

This lever setting positions blend-air door to direct flow of air through heater core (hot setting), around heater core (cold setting) or mixture of both. The lever also controls opening and closing of heater valve. At any setting except cold, heater valve is open, allowing engine coolant into heater.

BLOWER SWITCH

Switch controls speed of blower motor through resistor assembly. Either a dial knob or control lever may be used to select blower speeds.

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ADJUSTMENTS

INTAKE DOOR

1. Before installing intake door motor, ensure wiring harness connector of intake door motor is connected. Turn ignition on. Turn (depress) recirculation button on.
2. Install intake door motor and lever (if removed).

Set intake door rod in recirculated air position and fasten door rod to holder on intake door lever. Ensure intake door operates properly when recirculation button is pressed on and off.

MODE DOOR

1. Rotate side link by hand and hold mode door in vent position.

Install mode door motor, and connect wiring harness connector. Turn ignition on. Turn (depress) vent switch on.
2. Install rod of mode door motor to side link rod holder. Turn (depress) defrost switch on. Ensure side link operates at fully open position. Also turn (depress) vent switch on to ensure side link operates at fully open position.

TEMPERATURE CONTROL CABLE AND HEATER VALVE CONTROL ROD

Before adjusting heater valve control rod, disconnect temperature control cable from blend-air door. After adjusting control rod, install temperature control cable and adjust it as necessary.

1. Place temperature lever to maximum cold setting. Disconnect temperature control cable from air mix (blend-air) door lever.
2. Pull temperature control cable and air mix door lever toward retaining clip.

Secure cable using retaining clip.

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TESTING

BLOWER SPEED CONTROL SWITCH

Disconnect blower speed control switch (fan switch) connector. Check for continuity at specified terminals.

If continuity is not as specified, replace heater control assembly.

Switch Position

• OFF:
  • Continuity Between Terminals: No Continuity
• 1:
  • Continuity Between Terminals: 23, 27 & 28
• 2:
  • Continuity Between Terminals: 23, 26 & 28
• 3:
  • Continuity Between Terminals: 23, 25 & 28
• 4:
  • Continuity Between Terminals: 23, 24 & 28

REMOVAL AND INSTALLATION

Blower Motor

Disconnect battery. Disconnect blower wiring harness connector. Disconnect control cable from air intake door. Remove lower dash trim panel (if necessary). Remove blower motor screws. Remove blower motor. To install, reverse removal procedure.

Heater Control Assembly

1. Remove heater control bezel (if necessary). Remove radio. Remove heater control assembly (push control unit) screws.
2. Detach control cable from temperature control lever. Disconnect wiring harness connector. Remove heater control assembly. To install, reverse removal procedure. Adjust cables.

Heater control assembly removal and installation procedures for remaining models are not available from manufacturer.





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1989-1994 Nissan 240sx S13

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