1991 MITSUBISHI MONTERO Service Manual

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Switch Position Terminal Numbers Continuity
Colt Vista
OFF ......................... 1-7 ................. No
Low ...................... 1, 2 & 7 .............. Yes
Medium 1 ................... 2 & 4 ............... Yes
Medium 2 ................... 2 & 5 ............... Yes
High ....................... 2 & 6 ............... Yes
Montero
OFF ......................... 1-7 ................. No
Low ...................... 1, 2 & 7 .............. Yes
Medium 1 ................. 2, 4 & 7 .............. Yes
Medium 2 ................. 1, 5 & 7 .............. Yes
High ..................... 2, 6 & 7 .............. Yes
Pickup & Ram-50
OFF ......................... 1-6 ................. No
Low ...................... 1, 2 & 6 .............. Yes
Medium 1 ................. 1, 3 & 6 .............. Yes
Medium 2 ................. 1, 4 & 6 .............. Yes
High ..................... 1, 5 & 6 .............. Yes









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Fig. 6: Blower Switch Terminal ID (Pickup, Ram-50)
Courtesy of Mitsubishi Motor Sales of America.

Fig. 7: Front Blower Switch Terminal ID (Colt Vista & Montero)
Courtesy of Mitsubishi Motor Sales of America.
DUAL PRESSURE SWITCH
Montero, Pickup & Ram-50
1) Turn engine off. Disconnect harness connector at dual
pressure switch (located near condenser). Jumper harness connector.
Turn A/C switch and blower switch to ON positions. Momentarily turn
ignition on and listen for compressor clutch engagement.
2) If compressor clutch does not engage, check evaporator
thermistor and engine coolant temperature switch. Check for a faulty
fuse. Repair or replace components as necessary. If compressor clutch
engages, go to next step.
3) Connect manifold gauge set to system, and check operating
pressures. Dual pressure switch should allow compressor operation if
system pressure is 30-384 psi (2-27 kg/cm
). If dual pressure switch
does not operate within specified pressure range, discharge system
using approved refrigerant recovery/recycling equipment, and replace
switch.
4) After replacing switch, recharge system, and monitor
pressures for proper compressor operation. If dual pressure switch
cuts power to compressor clutch while driving even though temperatures
inside have not yet decreased, high pressure side of dual pressure
switch has possibly been activated. Go to next step.
5) Discharge system using approved refrigerant
recovery/recycling equipment. Replace switch, and recharge system.
Ensure compressor clutch operates within 30-384 psi (2-27 kg/cm
).
Check for sufficient system cooling.

ENGINE COOLANT TEMPERATURE SWITCH
1) Turn engine off. Disconnect connector at engine coolant
temperature switch. Jumper wires on harness side of connector. If
vehicle uses a single connector, ground connector.
2) Press A/C switch to ON position and turn blower switch to
ON position. Momentarily turn ignition on and listen for compressor
clutch engagement. Clutch should engage. If clutch does not engage,
check fuse and other components wired in series with compressor
clutch.
EVAPORATOR THERMISTOR
Disconnect connector and remove thermo relay from evaporator
core. Jumper wires on harness side connector. Turn A/C switch to ON
position and turn on blower. Momentarily turn ignition on and listen
for compressor clutch engagement. If clutch does not engage, check
fuse and other components wired in series with compressor clutch.
HIGH PRESSURE SWITCH
Colt Vista
Disconnect high pressure switch connector. Jumper wires on
harness side of connector. Momentarily turn ignition on and listen for
compressor clutch engagement. If clutch does not engage, check fuse
and other components wired in series with compressor clutch.
HIGH/LOW PRESSURE CUT-OFF SWITCH
Pickup & Ram-50
1) Turn engine off. Disconnect High/Low Pressure Cut-Off
(HLPCO) switch, located on refrigerant line near condenser. Jumper
HLPCO wiring harness connector. Turn A/C switch and blower switch to
ON positions. Momentarily turn ignition on and listen for compressor
clutch engagement.
2) If compressor clutch does not engage, check evaporator
thermistor and engine coolant temperature switch. Check for a faulty
fuse. Repair or replace as necessary. If compressor clutch engages, go
to next step.
3) Connect manifold gauge set to system, and check operating
pressures. HLPCO switch should allow compressor operation if system
pressure is 28-385 psi (1.9-27 kg/cm
). If HLPCO switch does not
operate within specified pressure range, discharge system using
approved refrigerant recovery/recycling equipment, and replace switch.
4) After replacing switch, recharge system, and monitor
pressures for proper compressor function. If HLPCO switch cuts power
to compressor clutch while driving even though temperatures inside
have not yet decreased, high pressure side of new HLPCO switch has
possibly been activated. Go to next step.
5) Discharge system using approved refrigerant
recovery/recycling equipment. Replace switch, and recharge system.
Ensure compressor clutch operates within 28-385 psi (1.9-27 kg/cm
).
Check for sufficient system cooling.
LOW PRESSURE SWITCH
Colt Vista
Disconnect low pressure switch connector. Jumper wires on
harness side of connector. Momentarily turn ignition on and listen for
compressor clutch engagement. If clutch does not engage, check fuse
and other components wired in series with compressor clutch.

COMPRESSOR CLUTCH
Disconnect wiring to compressor clutch. Connect battery
voltage directly to A/C compressor clutch wiring harness connector
terminals. If a click is heard, clutch engagement is okay. If click is
not heard, pulley and armature are not making contact. Repair or
replace as necessary.
REAR BLOWER SWITCH
Montero
With blower switch in position indicated in REAR BLOWER
SWITCH CONTINUITY TEST table, ensure continuity exists between
terminals listed. See Fig. 8.
REAR BLOWER SWITCH CONTINUITY TEST TABLE









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Switch Terminal
Position Numbers Continuity
OFF ................. 1-6 ................. No
Low .............. 1, 2 & 6 .............. Yes
Medium 1 ......... 1, 3 & 6 .............. Yes
Medium 2 ......... 1, 4 & 6 .............. Yes
High ............. 1, 5 & 6 .............. Yes









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Fig. 8: Identifying Rear Blower Switch Terminals (Montero)
Courtesy of Mitsubishi Motor Sales of America.
REFRIGERANT TEMPERATURE SENSOR
Disconnect refrigerant temperature sensor electrical
connector. Using an ohmmeter, measure resistance between terminals. At

77F (25C) resistance should be approximately 80,470 ohms. If
resistance deviates greatly, replace sensor.
RELAYS
4-Terminal Relay
1) Either round or square relays may be used. Testing is same
for either relay. Remove relay from holder. Using an ohmmeter, ensure
continuity exists between terminals No. 2 and 4 and does not exist
between terminals No. 1 and 3. See Fig. 9.
2) Connect battery voltage to terminal No. 2, and ground
terminalNo. 4. Ensure continuity exists between terminals No. 1 and 3.
If continuity is not as specified, replace relay.
Fig. 9: Testing 4-Terminal Relays
Courtesy of Mitsubishi Motor Sales of America.
6-Terminal Relay
Remove relay from holder. Using an ohmmeter, ensure

continuity exists between terminals No. 2 and 5 and terminals No. 1
and 3 and does not exist between terminals No. 3 and 6. Connect
battery voltage to terminal No. 2, and ground terminal No. 5. Ensure
continuity exists between terminals No. 3 and 6 and does not exist
between terminals No. 1 and 3. See Fig. 10. If continuity is not as
specified, replace relay.
Fig. 10: Testing 6-Terminal Relay
Courtesy of Mitsubishi Motor Sales of America.
REMOVAL & INSTALLATION
NOTE: For removal and installation procedures not covered in this

article, see appropriate HEATER SYSTEM article in the AIR
CONDITIONING & HEAT Section.
A/C SWITCH
Removal & Installation (Colt Vista)
From back side of control panel, push right control panel
clip right while pushing control panel out of dash panel. Allow
control panel to hang. Remove side bracket. Press temperature switch
control assembly left, and then remove A/C switch. To install, reverse
removal procedure.
Removal & Installation (Montero)
Remove lap heater duct. Remove glove box stoppers and glove
box. Remove heater control knobs. Remove center panel screw hole
plugs, and remove screws. Remove center panel. Disconnect center panel
wiring harness. Remove A/C switch. To install, reverse removal
procedure.
Removal & Installation (Pickup & Ram-50)
Remove heater control knobs. Remove glove box. Remove center
panel mounting screws. Use a trim stick to remove upper side of panel.
Remove A/C switch assembly mounting screws. Pull switch assembly
toward vehicle interior. Remove switch. To install, reverse removal
procedure.
COMPRESSOR
Removal & Installation (Colt Vista)
Discharge A/C system using approved refrigerant
recovery/recycling equipment. Disconnect high tension cable from
ignition coil. Remove distributor cap. Loosen idler pulley adjusting
bolt, and remove belt. Disconnect compressor electrical connector.
Remove high and low pressure lines and "O" rings from compressor.
Remove compressor mounting bolts. Remove compressor. To install,
reverse removal procedure.
Removal & Installation (Montero, Pickup & Ram-50)
DischargeA/C system using approved refrigerant
recovery/recycling equipment. Loosen idler pulley, and remove belt.
Disconnect compressor electrical connector. Disconnect high and low
pressure lines from compressor. Remove compressor mounting bolts.
Remove compressor. To install, reverse removal procedure.
CONDENSER
Removal & Installation (Colt Vista)
Discharge A/C system using approved refrigerant
recovery/recycling equipment. Remove front grille and grille brackets.
Remove front end cover and condenser harness. Disconnect electrical
fan connector. Slowly disconnect pressure lines from condenser. Remove
2 condenser mounting bolts. Lift up and remove condenser from vehicle.
To install, reverse removal procedure.
Removal & Installation (Montero)
Discharge A/C system using approved refrigerant
recovery/recycling equipment. Remove radiator grille. Slowly
disconnect pressure lines from condenser. Disconnect condenser fan
motor connector. Remove condenser fan mounting bolts and motor. Remove
condenser mounting bolts. Remove condenser from vehicle. To install,
reverse removal procedure.
Removal & Installation (Pickup & Ram-50)

Discharge A/C system using approved refrigerant
recovery/recycling equipment. Remove grille. Slowly disconnect
pressure lines at condenser. Remove upper condenser mounting bolts.
Remove condenser. To install, reverse removal procedure.
EVAPORATOR ASSEMBLY
Removal & Installation (Colt Vista)
1) Discharge A/C system using approved refrigerant
recovery/recycling equipment. Remove drain hose from evaporator.
Disconnect refrigerant line connections. Discard "O" ring seals.
2) Remove lower glove box and dash insert (or reinforcement)\
.
See Fig. 11 Remove upper glove box and duct joint. Remove defroster
ducts and duct joints from right side of evaporator. Disconnect A/C
harness connector and main harness connector. Remove evaporator
assembly. To install, reverse removal procedure.
Fig. 11: Removing Evaporator Assembly (Colt Vista)
Courtesy of Mitsubishi Motor Sales of America.
Removal & Installation (Montero)
1) Discharge A/C system using approved refrigerant