1991 MITSUBISHI MONTERO oil pressure

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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

\003
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

Fig. 9: Hitachi 6-Cylinder Compressor (5-Cylinder Similar)
Courtesy of Nissan Motor Co., U.S.A.
HITACHI 5 & 6-CYL SHAFT SEAL R & I
NOTE: Check compressor refrigerant oil level when replacing seals.
See COMPRESSOR REFRIGERANT OIL CHECKING article in this
section.
Removal
1) Drain oil from suction port, measure oil drained and
discard oil. Remove clutch hub, pulley, bearing assembly and coil
assembly. See HITACHI 5 & 6-CYLINDER CLUTCH R & I in this article.
2) Using snap ring pliers, remove retainer ring. Remove key
and plug low and high pressure openings of compressor with Plugs
(KV994C4531, KV994C4532 and KV994C4559).
3) Insert Adapter (KV994C1552) into hole in middle of blind

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.

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)

HEATER HOSES
HIGH PRESSURE RELIEF VALVES (HPRV)
IDLERS
IN-LINE FILTERS
METAL FITTINGS
METAL LINES
MIX AND AIR CONTROL DOORS (BLEND DOORS)
O-RINGS
ORIFICE TUBES
PILOT-OPERATED ABSOLUTES (POAS)
PLENUMS
PRESSURE CONTROL VALVES
PRESSURE SENSORS
PULLEYS
RADIATORS
RECEIVER-DRIERS
REFRIGERANT
REFRIGERANT OIL
RELAYS
SEALS
SERVICE PORTS
SPRING LOCK COUPLINGS
SUCTION THROTTLING VALVES (STVS)
SWITCHES (ELECTRICAL)
TENSIONERS
THERMISTORS AND PRESSURE SENSORS
THERMOSTATS AND HOUSINGS
VACUUM HOSES AND TUBES
VACUUM RESERVOIRS
VACUUM TUBES
VALVES IN RECEIVER (VIRS)
WATER PUMPS (ELECTRIC AUXILIARY)
WIRING HARNESSES AND CONNECTORS
MOTORIST ASSURANCE PROGRAM (MAP)
OVERVIEW
The Motorist Assurance Program is the consumer outreach
effort of the Automotive Maintenance and Repair Association, Inc.
(AMRA). Participation in the Motorist Assurance Program is drawn from
retailers, suppliers, independent repair facilities, vehicle
manufacturers and industry associations.
Our organization's mission is to strengthen the relationship
between the consumer and the auto repair industry. We produce
materials that give motorists the information and encouragement to
take greater responsibility for their vehicles-through proper,
manufacturer-recommended, maintenance. We encourage participating
service and repair shops (including franchisees and dealers) to adopt
(1) a Pledge of Assurance to their Customers and (2) the Motorist
Assurance Program Standards of Service. All participating service
providers have agreed to subscribe to this Pledge and to adhere to the
promulgated Standards of Service demonstrating to their customers that
they are serious about customer satisfaction.
These Standards of Service require that an inspection of the
vehicle's (problem) system be made and the results communicated to the\
customer according to industry standards. Given that the industry did
not have such standards, the Motorist Assurance Program successfully
promulgated industry inspection communication standards in 1994-95 for
the following systems: Exhaust, Brakes, ABS, Steering and Suspension,
Engine Maintenance and Performance, HVAC, and Electrical Systems.
Further, revisions to all of these inspection communication standards

missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Contaminated, affecting
performance ............ A ............ Require replacement.
Dessicant bag
deteriorated ........... A ........ (1) Require replacement.
Further inspection required.
Dessicant at the end of
its useful life (saturated
with moisture) ......... 1 .. Suggest repair or replacement.
Fusible plug leaking .... A .... Require replacement of plug.
Leaking ................. A ............ Require replacement.
Pressure relief device
leaking ................ A . Require replacement of pressure
relief device.
Restricted .............. A .. Require repair or replacement.
Sight glass no longer
transparent ............ 2 ... Suggest replacement of drier.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
Tubing connection
leaking ................ A .. Require repair or replacement.
( 1) - Inspect system to determine effects of dessicant bag
deterioration.









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REFRIGERANT
NOTE: Refrigerants include any SNAP (Significant New Alternative
Policy)-approved blends.
REFRIGERANT INSPECTION









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Condition Code Procedure
Contaminated (other than
refrigerant blends) .... B ........ Require service to remove
contamination.
Different types of
refrigerants in the same
system (other than
refrigerant blends) .... B ................. Require repair.
Overcharged ............. B ................. Require repair.
Refrigerant type
does not match
fittings and label ..... B ................. Require repair.
Undercharged ............ B ................. Require repair.









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REFRIGERANT OIL
REFRIGERANT OIL INSPECTION








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Condition Code Procedure
Contaminated ............ 1 .. Require repair or replacement.
Overfilled .............. B ................. Require repair.