1991 MITSUBISHI MONTERO air condition

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A/C C O M PR ESSO R O IL C HEC KIN G

1991 M it s u bis h i M onte ro
1991 GENERAL SERVICING
Compressor Refrigerant Oil Checking
ISOLATING COMPRESSOR
NOTE: Only compressors with stem-type service valves can be
isolated.
1) Connect service gauge set to the compressor service valves
and open compressor valves slightly (turn in clockwise). Start engine
and operate air conditioning. Slowly turn compressor suction valve
clockwise toward closed (front-seated) position.
2) When suction pressure is reduced to zero or less, turn off
engine and compressor and quickly turn suction valve stem in to full
front-seated position. Suction pressure should be slightly above zero.
Turn discharge valve into front-seated position.
3) To check oil level, slowly open compressor crankcase plug
to relieve any remaining pressure. After oil level is corrected, cap
service gauge ports on both valves. Back-seat suction service valve to
allow refrigerant to enter compressor. Open discharge valve halfway.
4) Loosen discharge service valve cap, allowing refrigerant
pressure to force air out of compressor. Back-seat service valve and
tighten cap. Compressor is now ready for operation.
REFRIGERANT OIL
Only new, pure, moisture-free refrigerant oil should be used
in the air conditioning system. This oil is highly refined and
dehydrated to a point where moisture content is less than 10 parts per
million. The oil container must be tightly closed at all times when
not in use, or moisture will be absorbed into the refrigerant oil from
the air.
SERVICING PRECAUTIONS
NOTE: Recent findings by the EPA indicate that refrigerant is
harmful to the earth's protective Ozone layer. When
discharging refrigerant, DO NOT allow refrigerant to enter
the atmosphere. If available, use refrigerant
recovery/recycle systems when discharging system. Always
follow manufacturer's instructions.
DISCHARGING SYSTEM PRECAUTIONS
If compressor has stem-type service valves, it can be
isolated and removed without discharging entire system. See ISOLATING
COMPRESSOR at the beginning of this article. Otherwise, discharge
system completely before loosening any fittings.
DISCONNECTING LINES & FITTINGS TEST
After system is discharged, carefully clean area around all
fittings to be opened. Always use 2 wrenches when tightening or
loosening fittings to avoid twisting or distorting lines. Cap or plug
all openings as soon as lines are removed. DO NOT remove caps until
immediately before connections are made. This will keep entry of air

and moisture to a minimum.
CONNECTING LINES AND FITTINGS
A new gasket or "O" ring should be used in all instances when
connecting lines or fittings. Dip "O" ring in new refrigerant oil and
ensure it is not twisted during installation. Always use 2 wrenches to
prevent damage to lines and fittings.
PLACING SYSTEM IN OPERATION
After component service or replacement has been completed and
all connections have been made, evacuate system thoroughly with a
vacuum pump. Charge system with proper amount of refrigerant and
perform a leak test. See REFRIGERANT OIL & R-12 SPECIFICATIONS chart
in this section for system capacities. Be sure to check all fittings
that have been opened. After system has been leak tested, make a
system performance check.
NOTE: Air conditioning systems will not normally need addition of
refrigerant oil unless definite oil loss has occurred due to
ruptured lines, leaking compressor seals, compressor
overhaul or component replacement.
ATSUGI ROTARY VANE DRAIN & REFILL
1) Before checking and adjusting oil level, operate
compressor at engine idling speed, with controls set for maximum
cooling and high blower speed, for 20 to 30 minutes to return oil to
compressor.
2) Stop engine, discharge refrigerant and remove compressor
from vehicle. See SERVICING PRECAUTIONS at beginning of article. Drain
compressor oil from compressor discharge port and measure the amount.
Oil is sometimes hard to drain when compressor is cool. Remove oil
while compressor is warm.
3) If the amount drained is less than 3 ounces, conduct leak
tests at system connections, and if necessary, repair or replace
faulty parts. Check purity of oil and adjust oil level as follows.
4) If amount drained was above 3 ounces, oil level is right.
Pour in same amount as was drained. If amount drained was below 3
ounces, pour in 3 ounces of new refrigerant oil.
BOSCH 6-CYL DRAIN & REFILL
1) Before checking and adjusting oil level, operate
compressor at engine idling speed, with controls set for maximum
cooling and high blower speed, for 20 to 30 minutes to return oil to
compressor.
2) Stop engine and discharge refrigerant. Remove refrigerant
oil level inspection plug on side of compressor. Oil should be at
lower lip of threaded hole. Add necessary new refrigerant oil (if
low). Replace inspection plug and tighten to 10-12 ft. lbs. (14-16 N.
m).
CALSONIC V5 5-CYLINDER
1) Before checking and adjusting oil level, operate
compressor at 1000-1500 engine RPM, and set controls at maximum
cooling and blowing speed for 20-30 minutes to return oil to

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A/C C O M PR ESSO R S ER VIC IN G

1991 M it s u bis h i M onte ro
1991 GENERAL SERVICING
Compressor Service
* PLEASE READ THIS FIRST *
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
ISOLATING COMPRESSOR
NOTE: Only compressors with stem-type service valves can be
isolated.
1) Connect service gauge set to the compressor service valves
and open compressor valves slightly (turn in clockwise). Start engine
and operate air conditioning. Slowly turn compressor suction valve
clockwise toward closed (front-seated) position.
2) When suction pressure is reduced to zero or less, turn off
engine and compressor and quickly turn suction valve stem in to full
front-seated position. Suction pressure should be slightly above zero.
Turn discharge valve into front-seated position.
3) To check oil level, slowly open compressor crankcase plug
to relieve any remaining pressure. After oil level is corrected, cap
service gauge ports on both valves. Back-seat suction service valve to
allow refrigerant to enter compressor. Open discharge valve halfway.
4) Loosen discharge service valve cap, allowing refrigerant
pressure to force air out of compressor. Back-seat service valve and
tighten cap. Compressor is now ready for operation.
REFRIGERANT OIL
Only new, pure, moisture-free refrigerant oil should be used
in the air conditioning system. This oil is highly refined and
dehydrated to a point where moisture content is less than 10 parts per
million. The oil container must be tightly closed at all times when
not in use, or moisture will be absorbed into the refrigerant oil from
the air.
DISCHARGING SYSTEM PRECAUTIONS
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
If compressor has stem-type service valves, it can be
isolated and removed without discharging entire system. Otherwise,
discharge system completely using approved refrigerant
recovery/recycling equipment before loosening any fittings.
DISCONNECTING LINES & FITTINGS TEST
After system is discharged, carefully clean area around all
fittings to be opened. Always use 2 wrenches when tightening or
loosening fittings to avoid twisting or distorting lines. Cap or plug
all openings as soon as lines are removed. Do not remove caps until

immediately before connections are made. This will keep entry of air
and moisture to a minimum.
CONNECTING LINES AND FITTINGS
A new gasket or "O" ring should be used in all instances when
connecting lines or fittings. Dip "O" ring in new refrigerant oil and
ensure it is not twisted during installation. Always use 2 wrenches to
prevent damage to lines and fittings.
PLACING SYSTEM IN OPERATION
After component service or replacement has been completed and
all connections have been made, evacuate system thoroughly with a
vacuum pump. Charge system with proper amount of refrigerant and
perform a leak test. See REFRIGERANT OIL & R-12 SPECIFICATIONS chart
in this section for system capacities. Be sure to check all fittings
that have been opened. After system has been leak tested, make a
system performance check.
NOTE: Air conditioning systems will not normally need addition of
refrigerant oil unless definite oil loss has occurred due to
ruptured lines, leaking compressor seals, compressor
overhaul or component replacement.
ATSUGI ROTARY VANE CLUTCH R & I
Removal
When replacing compressor clutch, be careful not to scratch
shaft or bend pulley. When removing center bolt, hold clutch disc with
Clutch Holder (KV99231010). Using Hub Puller (KV998VR001 &
KV99231010), remove clutch disc. When removing pulley, remove lock nut
with Hub Socket (KV99235160).
Installation
Wipe oil off clutch surface. Adjust disc pulley clearance to
.012-.024" (.3-.6 mm). Tighten center bolt to 80-104 INCH lbs. (9.1-
11.8 N.m). Tighten clutch lock nut to 22-29 ft. lbs. (29-39 N.m). See\
Fig. 1 .
Fig. 1: Atsugi Rotary Vane Compressor
Courtesy of Nissan Motor Co., U.S.A.
BOSCH 6-CYL CLUTCH R & I

Removal
1) Remove A/C compressor. Remove pressure plate shaft bolt
using socket wrench and Clutch Stopper (07112-76060). Install Clutch
Remover (07112-66040) on pressure plate. Using clutch stopper and
socket wrench, rotate clutch remover to remove pressure plate.
2) Remove shims from pressure plate. Remove snap ring from
compressor. Tap rotor off shaft with plastic hammer. Disconnect stator
wire from housing. Remove snap ring from inside stator. Remove stator.
See Fig. 12 .
CAUTION: DO NOT damage pulley when tapping on rotor.
Installation
To install, reverse removal procedure. Ensure snap rings are
installed with beveled side up. tighten shaft bolt to 10 ft. lbs.
(14 N.m). Ensure clutch clearance is .014-.026" (.36-66 mm). adjust
clearance by adding or subtracting shims as necessary.
NIPPONDENSO 6 & 10-CYL SHAFT SEAL R & I
NOTE: Check compressor refrigerant oil level when replacing seals.
See COMPRESSOR OIL CHECKING article in the AIR CONDITIONING &
HEAT section.
Removal
1) Hold clutch hub stationary and remove center nut. Screw
remover into center of hub. Turn center bolt to remove pressure plate.
2) Remove shims from shaft. Remove snap ring from inside of
pulley. Tap pulley off of shaft with plastic mallet. Be careful not to
distort pulley while removing.
3) Disconnect clutch coil wires from compressor housing.
remove snap ring inside coil and lift coil off compressor. Pry dust
seal out from around compressor shaft (if equipped).
4) Place shaft key remover on shaft and turn to remove key.
Remove drain plug (if equipped). Remove service valves-to-compressor
body bolts. Remove valves. Discard "O" rings. Drain oil out of
compressor.
5) Remove 6 through bolts from front head of compressor and
discard washers. Tap head loose from compressor; be careful not to
scratch sealing surfaces. remove snap ring (if equipped) from front
housing. Press seal plate out. Remove seal from shaft. See Fig. 14.
Installation
1) Lubricate shaft seal with clean refrigerant oil and place
on compressor shaft. Lubricate seal plate and "O" ring (if equipped)
and install in front housing. Install snap ring (if equipped).
2) Place front housing on compressor body. Install through
bolts with new washers. Tighten bolts evenly and alternately to
18 ft. lbs. (24 N.m). Install shaft key using installer and plastic
mallet. Insert dust seal into front of compressor.
3) Install drain plug with new gasket. Add correct amount of
refrigerant oil to compressor. If service valves were removed, coat
new "O" rings with refrigerant oil and install service valves.
4) Place clutch coil on compressor and install snap ring.
Install shims on shaft to adjust pressure plate-to-rotor clearance to
.016-.028" (.41-.71 mm). Tighten shaft nut to 12 ft. lbs. (16 N.m).

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A/C -H EA TE R S YSTE M - M AN UAL

1991 M it s u bis h i M onte ro
1991 MANUAL A/C-HEATER SYSTEMS
Chrysler Motors, Mitsubishi
Chrysler Motors: Colt Vista, Ram-50
Mitsubishi: Montero, Pickup
* PLEASE READ THIS FIRST *
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
A/C SYSTEM SPECIFICATIONS
SPECIFICATIONS TABLE








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Compressor Type
Colt Vista & Montero .................... Nippondenso 10-Cyl.
Pickup & Ram-50 ............................... Sanden Scroll
Compressor Belt Deflection
Colt Vista ............................ 11/32-7/16" (8-11 mm)
Montero ............................. 21/64-3/8" (8.5-9.5 mm)
Pickup & Ram-50 .................... 21/64-25/64" (8.5-10 mm)
Compressor Oil Capacity
Colt Vista & Montero ............................... 2.7 ozs.
Pickup & Ram-50 .................................... 5.0 ozs.
Refrigerant (R-12) Capacity
Colt Vista & Montero ................................ 32 ozs.
Pickup & Ram-50 ..................................... 30 ozs.
System Operating Pressures (1)
Colt Vista, Pickup & Ram-50
High Side .................... 130-220 psi (9.1-15.5 kg/cm
)
Low Side ........................ 20-26 psi (1.4-1.8 kg/cm)
Montero
Dual Unit
High Side .................. 142-199 psi (9.9-14.0 kg/cm
)
Low Side ...................... 16-30 psi (1.1-2.1 kg/cm)
Single Unit
High Side ................... 102-142 psi (7.1-9.9 kg/cm
)
Low Side ...................... 18-32 psi (1.3-2.2 kg/cm)
(1) - With ambient temperature at least 80
F (27C).








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DESCRIPTION
Slight variations exist among the manual A/C-heater systems
used. Either Sanden Scroll or Nippondenso 10-cylinder compressor is
used. Cycling of the compressor clutch is controlled by switches which
monitor temperatures and pressures.
Compressors will only operate within the normal operating
temperatures and pressures set for each model. An electric condenser
fan operates whenever A/C system is operating. System components used
vary depending upon model. Most systems include an A/C compressor
control unit, fan switch, evaporator, temperature sensor, high and low
(or dual) pressure switch, engine coolant temperature switch,
compressor, condenser, receiver-drier and various pipes and hoses.

OPERATION
A/C SWITCH
The A/C switch is located in the lower, center section of
control panel. See Fig. 1. When switch is pushed, air conditioning
will operate if blower motor control lever is in a position other than
OFF.
When activated, the A/C button/switch allows the A/C
compressor clutch to engage and operate the compressor. On some
models, a light on the button will glow when button/switch is
activated.
Fig. 1: A/C Switch & Control Panel
Courtesy of Mitsubishi Motor Sales of America.
AIR SELECTOR LEVER
The air selector lever is located in the upper, left corner
of control panel and moves horizontally to select the source of air
needed inside of passenger compartment. Lever moves from OFF position
on the left to the outside air mode, to the mixture of both outside
and inside air mode, and to the recirculation mode on the right. Lever
should normally be set in the recirculation mode for maximum A/C
cooling.
BLOWER MOTOR CONTROL LEVER
Blower motor control lever is located on the lower, left
corner of control panel and moves horizontally to select blower motor
speeds. As lever is moved from far left or OFF position, increasing

speeds of blower operation are selected. In order for A/C system to
operate, blower motor control lever MUST be in a position other than
OFF.
MODE SELECTOR LEVER
Mode selector lever is located in upper right corner of
control panel. Either 2 or 6 modes are available to achieve desired
distribution of air from various outlets.
On all models, air is directed to windshield and side
windows and comes out from the panel outlets when mode selector lever
is positioned to the far left. When lever is moved one detent to the
right, air is directed to windshield and side windows simultaneously.
On 6-mode models, air is directed to floor area, windshield,
and side windows when lever is moved 2 detents to the right. When
lever is moved 3 detents to the right, air is directed to floor area.
When lever is moved to the second to last detent on control panel, air
is directed to floor area and panel outlets. When lever is in the far
right position, air will be directed to panel outlets only.
TEMPERATURE CONTROL LEVER
The temperature control lever operates blend-air door in the
heater/air conditioning unit, mixing cooled and heated air so the
selected air temperature can be obtained. The system will provide
cooled air when A/C switch is in ON position and blower motor is in
any position other than OFF. The temperature control lever should be
in the far left (maximum cooling) side of temperature selection scale
when maximum A/C cooling is desired.
DUAL PRESSURE SWITCH
The dual pressure switch, located in the refrigerant line
near condenser, is wired in series with compressor clutch. Whenever
system pressures drop below or increase above the control point of the
switch, power supplied to compressor will be cut and compressor
activity will cease until pressures are back to within operating
ranges.
ENGINE COOLANT TEMPERATURE SWITCH
The engine coolant temperature switch, located on thermostat
housing, is wired in series with compressor clutch. When coolant
temperature is greater than switch control temperature, power to
compressor is cut and compressor is turned off until temperature
returns to operating range.
EVAPORATOR THERMISTOR
The evaporator thermistor, attached to evaporator fins, is
wired in series with compressor clutch and prevents evaporator
freezing. Power to compressor clutch is cut if control temperature is
exceeded, allowing evaporator to thaw. When temperature returns to
operating range, thermistor allows power to compressor clutch.
FUSIBLE PLUG
A fusible plug, located on receiver-drier, melts and allows
refrigerant to escape when ambient temperatures in engine compartment
reach 221
F (105C). Once fusible plug has blown, it cannot be reused
and must be replaced.