check engine MITSUBISHI MONTERO 1991 User Guide

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

compressor.
2) Stop engine. Discharge refrigerant and remove compressor
from vehicle. See SERVICING PRECAUTIONS at the beginning of this
article. Drain compressor oil from compressor discharge port and
measure oil amount. Oil may be hard to drain if compressor is cool.
Drain oil while compressor is warm.
3) If amount drained is less than 3.2 ounces, conduct leak
tests at system connections. Repair or replace faulty parts as
necessary. Check purity of oil and oil level as follows.
4) If amount drained is more than 3.2 ounces, oil level is
okay; fill with same amount drained using new oil. If amount drained
is less than 3.2 ounces, pour in 3.2 ounces of new refrigerant oil.
DIESEL KIKI 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 the beginning of this
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 is less than 2.4 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 2.4 ounces, oil level is
right. Pour in same amount as was drained. If amount drained was below
2.4 ounces, pour in 2.4 ounces of new refrigerant oil.
DIESEL KIKI 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, discharge refrigerant and remove compressor
from vehicle. See SERVICING PRECAUTIONS at the beginning of this
article. Remove oil drain plug and drain oil. Measure amount of oil
drained. Install drain plug with new "O" ring.
3) If amount drained was more than 2 ounces (4.4 ounces for
Infinity), refill with same amount of new oil. If amount drained was
less than 2 ounces (4.4 ounces for Infinity), refill with 2 ounces (4\
.
4 ounces for Infinity). Install filler plug and recharge system.
FORD FX-15 6-CYLINDER DRAIN & REFILL
NOTE: Replacement FX-15 compressors contain 7 ounces of refrigerant
oil. Prior to installing compressor, drain refrigerant oil
and determine proper amount of refrigerant oil to be added.
1) Slowly discharge system. Remove A/C compressor. Drain
compressor oil from suction and discharge ports. Measure amount
drained and discard oil.
2) If amount drained from removed (old) compressor is betwee\
n
3 and 5 ounces, add drained amount of new SUNINSO 5GS refrigerant oil
into the NEW compressor through suction port.
3) If amount drained is less than 3 ounces, add 3 ounces to
the NEW compressor. If amount drained is more than 5 ounces, add
5 ounces. Use new "O" rings on refrigerant lines. Install A/C

compressor. Evacuate and recharge system. Perform leak test.
HARRISON 4-CYL DRAIN & REFILL
NOTE: The Harrison compressor DOES NOT have an oil sump. It's
crucial that the compressor remains well oiled. It takes
very little time to destroy this compressor if it runs dry.
The Harrison 4-cyl compressor is charged (new) with 6 ounces
of refrigerant oil. Because compressor does not have an oil sump, it
should not have to be removed for oil measurement (it retains very
little oil). Note the following situations for checking and adding oil
to this compressor.
NO OIL LEAK; REPLACING COMPONENTS
If only the compressor is to be replaced, remove, drain oil,
measure and reinstall an equal amount of new oil. If evaporator is
being replaced, add 3 ounces of new oil. If condenser is being
replaced, add one ounce.
LOSS OF REFRIGERANT OVER EXTENDED PERIOD
When a loss of refrigerant has occurred over an extended
period of time and a component is being replaced to correct the leak,
add an appropriate amount of refrigerant oil to the component.
SIGNS OF EXCESSIVE OIL LEAKAGE
If system has lost excessive oil, remove accumulator. Drain
and measure oil. If more than 3 ounces is measured, replace the same
amount of new oil as was drained. If less than 3 ounces is measured,
add 3 ounces of new oil. Add and additional 2 ounces of new oil to
compensate for that lost by replacing the accumulator (held in
desiccant).
NOTE: If the exact oil charge is in doubt, drain and flush system.
Add a new 6-ounce charge of refrigerant oil to the system.
HARRISON V5 5-CYLINDER DRAIN & REFILL
1) If system is operable, run for several minutes to
stabilize system before performing repairs. Turn off engine. Discharge
system and remove compressor. See SERVICING PRECAUTIONS at the
beginning of this article. Remove drain plug. Drain and measure oil.
2) If more than one ounce is drained, add same amount. If
less than one ounce is drained, add 2 ounces of new refrigerant oil to
compressor.
3) If A/C components are replaced, add refrigerant oil to
system. Add one ounce if condenser is replaced. Add 3.5 ounces if
accumulator is replaced.
4) When replacing a component which has caused a large
refrigerant leak, add 3 ounces of new oil plus the required amount for
the part being replaced. Add oil directly to part being replaced if
possible. If oil can not be easily added to part, add oil to
accumulator.
NOTE: If oil drained contains metal chips or other debris, replace
receiver-drier. Flush out system before evacuating and
recharging.

HITACHI 5-CYL DRAIN & REFILL
1) Before checking and adjusting oil level, operate
compressor at 1000-1500 engine RPM, and set controls at maximum
cooling and high blowing speed for about 10 minutes to return oil to
compressor.
2) Stop engine. Discharge refrigerant and remove compressor
from vehicle. See SERVICING PRECAUTIONS at the beginning of this
article. Drain oil from compressor through suction port. Measure
amount of oil drained.
3) If amount drained is more than 2.4 ounces, fill with same
amount using new oil. If amount drained is less than 2.4 ounces, fill
with 2.4 ounces. Install compressor and recharge.
4) If A/C components are replaced. add refrigerant oil to
system. Add 1.7 ounces if condenser is replaced. Add 2.4 ounces if
evaporator is replaced. oil does not need to be added if receiver-
drier is replaced.
HITACHI 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 10 minutes to return oil to
compressor.
2) Stop engine, discharge refrigerant and remove compressor
from vehicle. See SERVICING PRECAUTIONS at the beginning of this
article. Drain oil from compressor suction port. Measure amount of oil
drained. If amount drained was more than 2.4 ounces, refill with same
amount of new oil. If amount drained was less than 2.4 ounces, refill
with 2.4 ounces. Install compressor and recharge.
MATSUSHITA ROTARY VANE DRAIN & REFILL
Discharge system. Remove compressor from vehicle. Drain oil
from compressor through inlet and outlet holes. Refill compressor with
3.4-4.7 ounces of oil through suction port. When replacing evaporator,
add 2 ounces. When replacing other A/C components, add 1.4 ounces per
component replaced.
NIPPONDENSO ROTARY VANE DRAIN & REFILL
1) Before checking and adjusting oil level, operate
compressor at engine idle speed, and set controls at maximum cooling
and high blowing speed for 20-30 minutes to return oil to compressor.
2) Stop engine. Discharge refrigerant and remove compressor
from vehicle. See SERVICING PRECAUTIONS at the beginning of this
article. Drain compressor oil through compressor intake and discharge
ports. Measure amount drained. Oil may be hard to drain if compressor
cool. Drain compressor while compressor is warm.
3) If amount drained is less than 2.4 ounces, conduct leak
tests at system connections. If necessary, repair or replace faulty
parts. Check purity of oil level and adjust oil level as follows.
4) If amount drained is more than 2.4 ounces, oil level is
okay; fill with same amount drained using new oil. If amount drained
is less than 2.4 ounces, pour 2.4 ounces of new refrigerant oil.
5) When replacing condenser, add one ounce. when replacing
other A/C components, add .33 ounce per container replaced.
NIPPONDENSO 6 & 10-CYL DRAIN & REFILL

When inspecting system for oil loss, look for signs of
leaking (shiny, wet spots on components or underside of hood). If oil
leak is noted or component replacement is required, use the following
procedure as indicated:
NO OIL LEAK
Discharge system and change components as necessary. See
SERVICING PRECAUTIONS at the beginning of this article. Add
refrigerant oil to components as necessary.
OIL LEAK
1) Slowly discharge system. Repair or replace faulty
components. If equipped with a drain plug, remove plug, drain and
discard oil. If not equipped with a drain plug, remove compressor from
vehicle and pour oil out suction and discharge ports.
2) Replace drain plug (if equipped). Add 1.5 ounces of new
refrigerant oil through suction port. Use new gaskets or "O" rings
when replacing suction and discharge lines.
COMPRESSOR FAILURE OR SYSTEM CONTAMINATED
If either situation exists, discharge system and remove
compressor, receiver-drier and expansion valve. Clean expansion valve
screen. Flush entire system. Install new compressor and receiver-
drier. New compressors contain correct amount of oil. If installing
overhauled compressor, add 1.5 ounces of new refrigerant oil through
suction port.
PANASONIC ROTARY VANE DRAIN & REFILL
1) Before checking and adjusting oil level, operate
compressor at 1000-1500 engine RPM, and set controls at maximum
cooling and high blowing speed for about 10 minutes to return oil to
compressor.
2) Stop engine. Discharge refrigerant and remove compressor
from vehicle. See SERVICING PRECAUTIONS at the beginning of this
article. Drain oil from compressor through suction and discharge
ports. Measure amount of oil drained. If amount drained is more than
2.4 ounces, fill with same amount using new oil. If amount drained is
less than 2.4 ounces, fill with 2.4 ounces. Install compressor and
recharge.
3) If A/C components are replaced, add refrigerant oil to
system. Add 1.4 ounces if condenser is replaced. Add 2 ounces if the
evaporator is replaced. Oil does not need to be added if receiver-
drier is replaced.
SANDEN SCROLL DRAIN & REFILL
Discharge system. Remove compressor from vehicle. Drain oil
from compressor through inlet and outlet holes. Refill compressor with
2.8 ounces of oil through suction port. When replacing condenser, add
.5 ounce. When replacing evaporator, add 1.7 ounces. When replacing
other A/C components, add .5 ounce per component replaced.
SANDEN 5-CYL DRAIN & REFILL
1) Discharge system. Remove compressor belt and loosen

mounting bolts. Rotate compressor in brackets until filler plug is at
top. Clean area around filler plug and remove plug slowly. Rotate
front hub plate so notch in lobe is 110 degrees from the bottom. This
rotates ball end of top piston to align with oil fill port and allows
clearance for dipstick. See Fig. 1.
2) Insert compressor dipstick diagonally from right to left
until stop on dipstick contacts filler plug surface. Remove dipstick
and note oil fill level. Each increment on dipstick represents one
ounce of oil. Add oil if necessary to reach 3-4 ounce level.
Fig. 1: Sanden 5-Cylinder Oil Level Checking
Courtesy of Sanden International U.S.A, Inc.
SANDEN 7-CYL DRAIN & REFILL
1) Before checking and adjusting oil level, operate
compressor at engine idle speed, and set controls at maximum cooling
and high blowing speed for 20-30 minutes to return oil to compressor.
2) Stop engine. Discharge refrigerant and remove compressor
from vehicle. See SERVICING PRECAUTIONS at the beginning of this
article. Remove oil drain plug and drain oil. Measure amount of oil
drained. Install drain plug with new "O" ring.
3) If amount drained is more than 3 ounces, fill with same
amount using new oil. If amount drained is less than 3 ounces, fill
with 3 ounces. Install filler plug. Install compressor and recharge
system.

\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

Check blower switch and relay. Check A/C compressor clutch coil.
2) Ensure system is properly charged with correct amount of
refrigerant. Add refrigerant or evacuate and recharge system as
necessary. Ensure receiver-drier is not clogged. Check compressor belt
for proper tension. Check for clogged expansion valve. Check
compressor operation. Repair or replace compressor as necessary.
INSUFFICIENT AIRFLOW
Check for air leakage at air duct joint. Check for frost on
evaporator. Ensure blower motor is operating properly. Check for
obstructed air intake.
INSUFFICIENT COOLING
Ensure system is properly charged with correct amount of
refrigerant and free of air and moisture. Add refrigerant or evacuate
and recharge system as necessary. Ensure receiver-drier is not
clogged. Ensure sufficient airflow through condenser exists. Check
compressor belt for proper tension. Check compressor operation. Repair
or replace compressor as necessary. Check for clogged expansion valve.
Replace expansion valve as necessary.
INTERMITTENT COOL AIR
Check for air or moisture in system. Evacuate and recharge
system as necessary. Check for expansion valve malfunction. Replace
expansion valve if necessary. Check compressor belt for proper
tension.
TESTING
A/C SWITCH
1) Disconnect A/C switch harness connector. Using appropriate
wiring diagram as a guide, jumper appropriate terminals of A/C switch
wiring harness connector. See Fig. 4.
2) Turn blower on and momentarily turn ignition on without
starting engine. Listen for compressor clutch engagement. If
compressor clutch does not engage, check fuse and other components
wired in series with compressor clutch.
Fig. 4: A/C Switch Connector ID
Courtesy of Mitsubishi Motor Sales of America.
AIR THERMO & AIR INLET SENSORS

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.