MAZDA MIATA 1991 Factory Service Manual

Fig. 1: Testing A/C & Blower Switch
Courtesy of MAZDA MOTORS CORP.
A/C RELAY
1. Remove relay. Check continuity between specified terminals of relay connector. See A/C RELAY TEST
table. See Fig. 2 . Ensure test lead polarity is correct. If continuity is not as specified, replace relay.
2. If continuity is as specified, apply battery positive lead to terminal "D" and negative lead to terminal "A".
Check continuity between terminals "E" and "C". If there is continuity, relay is okay. If there is no
continuity, replace relay.
A/C RELAY TEST
Fig. 2: A/C Relay Connector Terminal ID

Courtesy of MAZDA MOTORS CORP.
Terminal (+)(1) Terminal (-)(2) Continuity
ABYes
ADYes
BANo
CENo
DANo
ECYes
(1)Connect ohmmeter positive lead to this terminal.
(2)Connect ohmmeter negative lead to this terminal.

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A/C-HEATER SYSTEM - MANUAL 1990-92 Manual A/C-Heater Systems
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BLOWER MOTOR
Disconnect 2-wire connector from bottom of blower motor case. Apply battery voltage across blower motor
terminals. Replace blower motor if it does not operate.
BLOWER RESISTOR
Note 4-wire connector and 1-wire connector attached to seam where upper and lower blower cases meet. Wires
in these connectors lead to blower resistor on bottom of blower case. Disconnect both connectors. If continuity
does not exist between 1-wire connector terminal and each terminal of 4-wire connector, replace blower
resistor.
CONDENSER (ADDITIONAL) FAN MOTOR
Disconnect condenser fan connector. Apply battery voltage across condenser fan terminals. Replace condenser
fan motor if it does not operate.
EVAPORATOR THERMOSWITCH
1. Remove glove box. Run engine at idle. Turn off A/C switch. Turn blower switch to 4th position (high) for
a few minutes to ensure evaporator temperature is greater than 32°F (0°C). Turn off blower switch and
engine.
2. Disconnect evaporator thermoswitch connector. Check continuity between switch terminals. If there is
continuity, thermoswitch is okay. If there is no continuity, replace thermoswitch.
PRESSURE SWITCH
1. Turn ignition off. Connect manifold pressure gauges to system. If high-side pressure is less than 31.2 psi
(2.2 kg/cm
2 ), check system for proper refrigerant charge.
2. If high-side pressure is greater than 31.2 psi (2.2 kg/cm
2 ), disconnect pressure switch connector. Check
continuity between switch terminals. If there is continuity, switch is okay. If there is no continuity,
replace switch.
REMOVAL & INSTALLATION
AIR BAG WARNING
BLOWER CASE
Removal & Installation
WARNING:To avoid injury from accidental air bag deployment, read and carefully
follow all SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR
BAG SYSTEM procedures in AIR BAG article in the
ACCESSORIES/SAFETY EQUIPMENT Section.

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A/C-HEATER SYSTEM - MANUAL 1990-92 Manual A/C-Heater Systems
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Disconnect electrical connectors from blower case. Remove glove box. Loosen seal plate between blower motor
case and evaporator case. Remove blower motor case nuts. Remove case and seal plate. To install, reverse
removal procedure.
COMPRESSOR
Removal & Installation
1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling
equipment. Disconnect compressor clutch connector. Disconnect refrigerant lines from compressor.
Remove drive belt.
2. Raise and support vehicle. Remove compressor mounting bolts and remove compressor. To install,
reverse removal procedure. Adjust drive belt to specified tension. Evacuate and charge system.
CONDENSER & RECEIVER-DRIER
Removal & Installation
Discharge A/C system using approved refrigerant recovery/recycling equipment. Raise and support vehicle.
Remove splash shield and air guide. Remove condenser and receiver-drier as an assembly. To install, reverse
removal procedure. Evacuate and charge system.
CONTROL PANEL
Removal & Installation
Remove rear console assembly. See Fig. 4 . Remove vent outlets from center panel assembly. Remove center
panel assembly. Remove control panel screws. Pull control panel from hole. Disconnect door control cables
from back of control panel and remove panel. To install, reverse removal procedure.
EVAPORATOR CORE & THERMOSWITCH
Removal & Installation
1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove condenser and
receiver-drier as an assembly. Disconnect low-pressure and high-pressure pipes from evaporator tubes at
engine compartment firewall.
2. Remove right undercover and glove box. Disconnect thermoswitch electrical connector. Loosen left seal
plate (between heater case and evaporator case). Loosen right seal plate (between evaporator case and
blower motor case).
3. Remove evaporator case. Disassemble evaporator case, and remove evaporator core and thermoswitch.
See Fig. 3
. To install, reverse removal procedure. Evacuate and charge system.

1991 Mazda MX-5 Miata
A/C-HEATER SYSTEM - MANUAL 1990-92 Manual A/C-Heater Systems
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Fig. 3: Exploded View of Evaporator Case
Courtesy of MAZDA MOTORS CORP.
HEATER CORE
Removal & Installation
Drain coolant. Disconnect heater hoses at engine compartment firewall. Remove grommets from holes (if
equipped). Remove instrument panel. Remove heater case. Disassemble case and remove heater core. See Fig.
1 . To install, reverse removal procedure. Fill cooling system.
INSTRUMENT PANEL

1991 Mazda MX-5 Miata
A/C-HEATER SYSTEM - MANUAL 1990-92 Manual A/C-Heater Systems
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Removal & Installation
Obtain code number and deactivate audio anti-theft system. Disconnect negative battery cable. Remove all
components in order listed in illustration. See Fig. 4
. To install, reverse removal procedure.
Fig. 4: Exploded View of Instrument Panel

Courtesy of MAZDA MOTORS CORP.
WIRING DIAGRAMS

1991 Mazda MX-5 Miata
A/C-HEATER SYSTEM - MANUAL 1990-92 Manual A/C-Heater Systems
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Fig. 5: Manual Heater-A/C System Wiring Diagram (1990)
Fig. 6: Manual Heater
-A/C System Wiring Diagram (1991)

1991 Mazda MX-5 Miata
A/C-HEATER SYSTEM - MANUAL 1990-92 Manual A/C-Heater Systems
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Fig. 7: Manual Heater-A/C System Wiring Diagram (1992)

1991 Mazda MX-5 Miata
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STEERING GEAR - POWER RACK & PINION
1991 STEERING Mazda - Power Rack & Pinion
DESCRIPTION
Steering system is a power-assisted rack and pinion. The system consists of a rack and pinion steering gear and
power-assist pump/reservoir. The steering gear and pump/reservoir are connected by flexible hoses.
TESTING
HYDRAULIC SYSTEM PRESSURE TEST
Pump Fluid Pressure Test
1. Disconnect pressure hose and connect pressure gauge/valve between steering pump and steering gear. See
Fig. 1
. Bleed air from system.
2. Open valve fully. Start engine and idle. Turn steering wheel lock-to-lock to increase fluid temperature to
122-140°F (50-60°C). To measure pump fluid pressure, close gauge valve completely.
3. Increase engine speed to 1000-1500 RPM. Ensure pump pressure is within specification. See
HYDRAULIC SYSTEM FLUID PRESSURE SPECIFICATIONS
table. If pressure is not within
specification, replace pump.
CAUTION: DO NOT leave gauge valve closed for more than 15 seconds, or pump may
be damaged.

1991 Mazda MX-5 Miata
STEERING GEAR - POWER RACK & PINION 1991 STEERING Mazda - Power Rack & Pinion

1991 Mazda MX-5 Miata
STEERING GEAR - POWER RACK & PINION 1991 STEERING Mazda - Power Rack & Pinion
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Fig. 1: Connecting Pressure Gauge (Except 4-Wheel Steering)
Courtesy of MAZDA MOTORS CORP.
Gear Fluid Pressure Test
1. Ensure pump pressure is within specification. To measure steering gear fluid pressure, open gauge/valve
completely. Increase engine speed to 1000-1500 RPM.
2. Turn steering wheel from lock-to-lock. Gauge pressure must be within specification. See HYDRAULIC
SYSTEM FLUID PRESSURE SPECIFICATIONStable. If pressure is less than specification, steering
gear is defective.
HYDRAULIC SYSTEM FLUID PRESSURE SPECIFICATIONS
(1)
Applicationpsi (kg/cm2 )
Miata1109-1209 (78-85)
MPV, MX-6, 626 & 9291067-1138 (75-80)
Protege
2WD1067 (75)
4WD1138 (80)
RX71138-1209 (80-85)
3231067 (75)

1991 Mazda MX-5 Miata
STEERING GEAR - POWER RACK & PINION 1991 STEERING Mazda - Power Rack & Pinion
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LUBRICATION
CAPACITY
POWER STEERING FLUID CAPACITY
FLUID TYPE
Dexron-II or M-III are recommended for all vehicles.
FLUID LEVEL CHECK
Check fluid level with engine off. Remove fluid level gauge on oil pump or reservoir. Check fluid level. Fluid
should be between "L" and "H" marks on level gauge dipstick. If fluid level is low, fill through gauge tube.
Recheck fluid level. DO NOT overfill.
HYDRAULIC FLUID BLEEDING
1. Raise and support front of vehicle. With ignition off, turn steering wheel lock-to-lock several times. Add
fluid as necessary. Repeat procedure until fluid level no longer decreases.
2. Start engine and let idle. Turn steering wheel lock-to-lock 5 times. Check fluid level. Add fluid as
necessary. Continue procedure until fluid is clear of air bubbles and does not decrease in level.
ADJUSTMENTS
POWER STEERING BELT ADJUSTMENT
POWER STEERING BELT DEFLECTION
(1)
(1)Specifications are measured at 1000-1500 RPM, with fluid temperature at 122-140°F (50-60°C).
ApplicationQts. (L)
Miata, MPV & 929.95 (.90)
MX-6 & 626
Electronc Controlled Power Steering (ECPS)1.06 (1.0)
Engine Speed (Sensing) Power Steering (ESPS).95 (.90)
Protege & 323.63 (.60)
RX7.85 (.80)
NOTE: On-vehicle adjustment procedures are not available from manufacturer.
ApplicationIn. (mm)
Miata, Protege & 323
New Belt.31-.35 (7.8-8.9)

1991 Mazda MX-5 Miata
STEERING GEAR - POWER RACK & PINION 1991 STEERING Mazda - Power Rack & Pinion
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