HEATER CORE

Miata

REMOVAL AND INSTALLATION

1997 Models

NOTE: If equipped with an air bag or anti-theft coded radio, disable the air bag system and obtain the radio theft codes before proceeding.

1. Disconnect the negative battery cable.
2. Drain the engine coolant into a clean container for reuse.
3. Remove or disconnect the following:
   • Heater hoses from the heater core
   • Transmission selector lever or knob
   • Center console
   • Steering wheel
   • Upper and lower steering column covers. Remove the combination switch
   • Instrument meter hood
   • Instrument cluster assembly
   • Speedometer cable
   • Heater ducts
   • Instrument housing lower panels
   • Glove box assembly
   • Heater control switch and cables
   • Header and the side trim, if required
   • Center cap, the side covers and the center bracket bolts on the instrument panel
   • Steering shaft bolts
   • Any necessary wire harness connectors
   • Instrument panel
   • Seal plate
   • Attaching nuts
   • Heater unit
   • Attaching clips on the heater unit and separate the assembly
   • Heater core

     Fig. 1: Exploded view of the instrument panel assembly — 1997 Miata

   To install:

4. Install or connect the following:
   • Heater core into the heater unit
   • Heater case halves with the clips
   • Heater unit. Install the seal plates
   • Instrument panel
   • Wiring harness connectors
   • Steering shaft bolts
   • Center cap, the side covers and the center bracket bolts on the instrument panel
   • Header and side trim, if removed
   • Heater control switch and cables
   • Glove box assembly
   • Instrument housing lower panels
   • Heater ducts
   • Speedometer cable
   • Instrument cluster and meter hood assembly
   • Upper and lower steering column covers
   • Steering wheel
   • Center console and the shift lever or knob
   • Heater core hoses
   • Negative battery cable
5. Refill the cooling system.
6. Operate the engine to normal operating temperatures; then, check the climate control operation and check for leaks.

1998-01 Models

1. Disconnect the negative battery cable.

   CAUTION
   After disconnecting the battery, wait for more than 1 minute for the SAS to deplete its stored energy.

2. Drain the cooling system into a clean container for reuse.
3. Disconnect the heater hoses from the heater core.
4. Discharge and recover the air conditioning system refrigerant.
5. At the driver's side, remove the SAS module and the steering wheel by removing or disconnecting the following:
   • Place the wheel in the straight-ahead position and turn the ignition switch to LOCK
   • Cover clips at both sides of the steering wheel
   • Steering wheel-to-SAS module bolts
   • SAS module from the steering wheel and disconnect the electrical connector
   • Steering wheel-to-column nut
   • Steering wheel from the steering column using a suitable puller
6. At the passenger's side, remove the SAS module by removing or disconnecting the following:
   • Glove compartment and the glove compartment cover
   • SAS module-to-dash bolts
   • SAS module and disconnect the electrical connector
   • Console
7. Remove the instrument cluster by removing or disconnecting the following:
   • A-pillar trim at both sides
   • Lower panel
   • Instrument cluster hood
   • Instrument cluster-to-dash screws and the instrument cluster
   • Hood release lever
   • Control wire from the heater unit and the blower unit
   • Steering column-to-instrument panel bolts and lower the steering column
   • Instrument panel-to-chassis bolt covers and the bolts
   • Instrument panel with the help of an assistant
8. Remove or disconnect the following:
   • Heater unit-to-evaporator housing seal plate
   • Heater unit-to-chassis nuts and the heater unit
9. Separate the heater unit cases and remove the heater core.

   Fig. 2: View of the SAS module and the steering wheel - 1998-01 Miata

   Fig. 3: View of the passenger's side SAS module - 1998-01 Miata

   Fig. 4: View of the instrument panel - 1998-01 Miata

   Fig. 5: View of the console - 1998-01 Miata

   Fig. 6: View of the heater unit and the heater unit-to-evaporator unit seal plate - 1998-01 Miata

   Fig. 7: Exploded view of the heater core and heater unit assembly - 1998-01 Miata

   To install:

10. Install the heater core and assemble the heater unit cases.
11. Install or connect the following:
    • Heater unit-to-chassis nuts and the heater unit
    • Heater unit-to-evaporator housing seal plate
12. Install the instrument cluster by installing or connecting the following:
    • Instrument panel with the help of an assistant
    • Instrument panel-to-chassis bolt covers and the bolts
    • Steering column-to-instrument panel bolts
    • Control wire to the heater unit and the blower unit
    • Hood release lever
    • Instrument cluster and the instrument cluster-to-dash screws
    • Instrument cluster hood
    • Lower panel
    • A-pillar trim at both sides
    • Console
13. At the passenger's side, install the SAS module by installing or connecting the following:
    • SAS module and connect the electrical connector
    • SAS module-to-dash bolts
    • Glove compartment cover and the glove compartment
14. At the driver's side, install the SAS module and the steering wheel by installing or connecting the following:
    • Steering wheel-to-column nut. Torque the steering wheel nut to 29-36 ft. lbs. (40-49 Nm)
    • SAS module to the steering wheel and connect the electrical connector
    • Steering wheel-to-SAS module bolts. Torque the steering column-to-SAS module bolts to 70-104 inch lbs. (8-12 Nm)
    • Cover clips at both sides of the steering wheel
15. Connect the heater hoses to the heater core.
16. Refill the cooling system.
17. Connect the negative battery cable.
18. Evacuate, charge and leak test the air conditioning system refrigerant.
19. Operate the engine to normal operating temperatures; then, check the climate control operation and check for leaks.