low oil pressure PONTIAC FIERO 1988 Service Repair Manual

OB-4 MAINTENANCE AND LUBRICATION
Tire and wheel operation - Be alert to a vibra-
tion of the steering wheel or seat at normal highway
speeds. This may mean a wheel balance is needed. Also, a
pull right or left on a straight, level road may show the
need for
a tire pressure adjustment or wheel alignment.
Steering system operation - Be alert to
changes in steering action. An inspection is needed when
the steering wheel is harder to turn or has too much free
play or if unusual sounds are noted when turning or
parking.
Headlight aim operation - Take note of light
pattern occasionally. If beam aim doesn't look right,
headlights should be adjusted.
AT EACH FUEL FILL
Engine oil level check - Check engine oil level
and add if necessary. See your Owner's
Manual for further
details.
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Engine coolant level and condition - Check
engine coolant level in coolant reservoir tank and add if
necessary. Replace if dirty or rusty. See your Owner's
Manual for further details.
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Windshield washer fluid level check -- Check
washer fluid level in container and add if necessary.
Hood latch operation - When opening hood on
cars equipped with hoods that open from the front, note
the operation of secondary latch. It should keep hood from
opening all the way when primary latch is released. Make
sure that hood closes firmly.
AT LEAST MONTI-ILY
Tire and wheel inspection and pressure
check--
Check tires for abnormal wear or damage. Also,
check for damaged wheels. Keep pressures as shown on
Tire Placard on the driver's door (include spare unless it is
a stowaway). Pressure should b\: checked when tires are
"cold". See "Tires" in Owner's Manual for further
infomation.
Light operation check - Check operation of
license plate light, side-marker lights, headlights includ-
ing high beams, parking lights, taillights, brake lights.
turn signals, backup lights, instrument panel and interior
lights and hazard warning flashers.
Fluid leak check - After the car has been parked
for a while, inspect the surface beneath the car for water,
oil, fuel or other fluids. Water dripping from the air
conditioning system after use is normal. If you notice fuel
leaks or fumes, the cause should be found and corrected at
once.
AT LEAST TWICE A YEAR (FOR EXAMPLE,
EVERY SPRING AND FALL)
Power steering pump fluid level check --
Check power steering pump fluid level in accordance with
Owner's Manual instructions and keep at proper level.
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Brake master cylinder reservoir fluid level
check ---- Check fluid and keep at proper level. Note: It is
normal for the brake fluid level to go down slightly as the
brake pads wear
- so be sure to keep reservoir filled.
NOTICE: A large loss in this system may indicate a
problem. Have
it inspected and repaired at once.
Clutch system service --- manual transmis-
sionltransaxle --- For cars equipped with hydraulic
clutch system, check the reservoir fluid level and add fluid
as required. All others, check clutch pedal free travel and
adjust as necessary. See your Owner's Manual for further
details.
~
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Weatherstrip Lubrication - Clean surface and
then apply a thin film of silicone grease with a clean cloth.
EACH TIME OIL IS CHANGED
Automatic and manual transmissionltrans-
axle fluid level check - Check transmission/transaxle
fluid level and add as required. (Corvette only) if equipped
with manual transmission
- check fluid in the overdrive
unit and add as required.
NOTICE: A large loss in this system may indicate a
problem. Have
it inspected and repaired at once.
Brake systems inspection - For convenience,
the following should be done when wheels are removed
for rotation: Inspect lines and hoses for proper hookup,
binding, leaks, cracks, chafing, etc. Inspect disc brake
pads for wear and rotors for surface condition. Also in-
spect drum brake linings for wear and cracks. Inspect
other brake parts, including drums, wheel cylinders, park-
ing brake, etc. at the same time. Check parking brake
adjustment.
INSPECT BRAKES MORE OFTEN IF DRIVING
HABITS OR CONDITIONS RESULT IN FREQUENT
BRAKING.
Steering, suspension and front drive axle
boot and seal inspection
- Inspect front and rear
suspension and steering system for damaged, loose or
missing parts, signs of wear or lack of lubrication. Inspect
power steering lines and hoses for proper hookup, bind-
ing, leaks, cracks, chafing, etc. (On cars equipped with
manual steering gear, check for seal leakage.) On
front-
wheel-drive cars, clean then inspect drive axle boot seals
for damage, tears or leakage. Replace seals if necessary.
Exhaust system inspection - Inspect complete
system. Inspect body near the exhaust system. Look for
broken, damaged, missing or out-of-position parts as well
as open seams, holes, loose connections or other condi-
tions which could cause a heat buildup in the tloor pan or
could let exhaust fumes seep into the trunk or passenger
compartment.

MAINTENANCE AND LUBRICATION OB-5
Throttle linkage inspection -- Inspect for inter-
ference, binding, damaged or missing parts.
Engine drive belts inspection - Inspect all
belts for cracks, fraying and wear. Adjust or replace as
needed.
Rear axle service (if equipped) - Check gear
lubricant level and add if needed. For cars equipped with a
limited slip rear axle, fluid does not require changing
(except Caprice and Corvette
- change fluid and required
additive at first
7,500 miles (12 500 km). See your
Owner's Manual or "Recommended Fluids
& Lubricants
Chart" in this section.
IF YOU USE YOUR GAR TO PULL A TRAILER,
CHANGE GEAR LUBRICANT EVERY 7,500 MILES
(12 500 KM).
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Power antenna - Clean and then lubricate power
antenna mast. The proper lubricant as shown in Figure
OB-2 should be used.
AT LEAST ONCE A YEAR
Lap and shoulder belts condition and opera-
tion
- Inspect belt system, including webbing, buckles,
latch plates, retractors, guide loops and anchors.
Moveable head restraint operation - On cars
with moveable restraints, make sure restraints stay in the
desired position. (See adjustment instructions in your
Owner's Manual.)
Seatback latch and recliner operation on
cars equipped
with recliner seat --- Be sure seat-
backs latch on those cars with folding seats using mechan-
ical latches. Make sure the recliner is holding by pushing
and pulling on the top of the
seatback while it is reclined.
See your Owner's Manual for seat operating information.
Spare tire and jack storage- Be alert to rattles
in rear of car. Make sure the space tire, all jacking equip-
ment, any tire inflator and any covers or doors are securely
stowed at all times. Oil jack ratchet or screw mechanism
after each use.
Key lock service - Lubricate key lock cylinder at
least annually.
Body lubrication service - Lubricate all body
door hinges including the tailgate or hatchback lid (if
equipped). Also lubricate the body hood, fuel door and
rear compartment hinges and latches including interior
glove box and counsel doors, and any folding seat
hardware.
"Fansmissionltransaxle neutral or clutch
starl switch operation
CAUnON: Before pedorming the follow-
ing safety switch check, be sure to have
enough room around the car. Then, firmly
apply both the parking brake (see your
Owner's Manual for procedure) and the
regular brakes. Do not use the accelerator pedal.
If the engine
starls, be ready to turn
off the ignition promptly. Take these pre-
cautions because the car could move
without warning and possibly cause per-
sonal injury or properly damage. On auto-
matic transmissionltransaxle cars, try to
starl the engine in each gear. The starler
should crank only in "Park" or "Neutral."
On manual transmissionltransaxle cars,
place the
shiR lever in "Neutral," push the
clutch halfway and try to starl. The starler
should crank only when the clutch is fully
depressed.
Steering column lock operation
- While
parked, try to turn key to "Lock" in each gear range. The
key should turn to "Lock" only when gear is in "Park" on
automatic or "Reverse" on manual
transmissionltransax-
le. On cars with key release lever, try to turn key toULock"
without depressing the lever. The key should turn to
"Lock" only with the key lever depressed. On all vehicles,
the key should come out only in "Lock."
Parking brake and transmissionltransaxle
"Park" mechanism operation
CAUT1ON:Before checking the holding
ability of the parking brake and automatic
transmissionltransaxle "Park" mecha-
nism, park on a fairly steep hill with
enough room for movement in the down-
hill direction. To reduce the risk of person-
al injury or property damage, be prepared
to apply the regular brakes promptly if the
car begins to move.
To check the parking brake, with the engine running and
transmission/transaxle in "Neutral." slowly remove foot
pressure from the regular brake pedal (until the car is held
by only the parking brake).
To check the automatic transmissionltransaxle "Park"
mechanism holding ability, release all brakes after shift-
ing the transmissionltransaxle to "Park."
ljnderbody flushing - At least every spring,
tlush from the underbody with plain water any corrosive
materials used for ice and snow removal and dust control.
Take care to thoroughly clean any areas where mud and
other debris can collect.
Sediment packed in closed areas
of the vehicle should be loosened before being flushed.
Engine cooling system service - Inspect
coolant and freeze protection. If dirty or rusty, drain, flush
and refill with new coolant. Keep coolant
at the proper
mixture as specified in your Owner's Manual. This pro-
vides proper freeze protection. corrosion inhibitor level
and engine operating temperature. Inspect hoses and re-
place if cracked. swollen or deteriorated. Tighten hose
clamps. Clean outside of radiator and air conditioning
condensor. Wash radiator filler cap and neck.
To help
ensure proper operation. a pressure test of both the cooling
system and cap is also recommended. (See maintenance
schedule charts in Figure
OB-l for the recommended
coolant change interval.)

AIR CONDITIONING 1B-1
SECTION 1B
R COND
When performing air conditioning diagnosis on vehicles equipped with a catalytic converter, it will be necessary to
WARM the engine to a NORMAL operating temperature BEFORE attempting to idle the engine for periods greater
than five
(5) minutes. Once the engine attains normal idle, diagnosis and adjustments can be made.
CONTENTS
.................. General Description .................................. 1B-1 Accumulator Assembly Service .1B-19
.......................... C.C.O.T. A!C System ................................ 1B-1 On-Vehicle Sewice ..... 1B-20
....................................... System Components - Functional ................. 1B-2 Blower Motor .1B-20
..................................... System Components - Control ..................... 1B-3 Hi-Blower Relay 1B-20
...................................... Relays and Switches ................................... 1B-3 Blower Resistor 1B-20
Diagnosis ................................................. 1B-5 Controller, Blower Switch or Vacuum
................................................ Testing the Refrigerant System ...................... 1B-5 Valve .lB-20
Insufficient Cooling "Quick-Check Temperature Control Cable ....................... .1B-20
.................................... Procedure.. ............................................. 1B-5 Vacuum
Harness .lB-20
C.C.O.T. A/C System Diagnostic Control Wiring Harness ........................... .1B-20
..... ................................. Procedure.. ............................................. 1B-8 Heater
Core .. .lB-21
................................ Leak Testing ........................................... 1B-12 Lower Heater Outlet 1B-21
............................... Service Procedures ................................. .1B-12 Heater Module Case .lB-21
.......................... O-Ring Replacement ................................ .1B- 12 Pressure Cycling Switch .1B-21
....................................... Handling Refrigerant- 12 ............................ .1B- 13 Vacuum Tank .lB-21
Discharging, Adding Oil, Evacuating Liquid Line .......................................... .1B-23
and
Charging Procedures - AIC Accumulator ......................................... .1B-23
.................................... Systems .............................................. .1B-14 Evaporator Core .1B-24
In-Line Air Conditioning Evaporator Case .................................... .1B-24
.......................................... Filter
Installation.. .................................. .1B- 18 Compressor .lB-24
.............................................
................ Expansion Tube (Orifice) Service .1 B- 19 Condenser IB-24
GENERAL DESCRIPTION
All engines are equipped with a fixed displace- evaporator temperature. The pressure cycling switch
ment (R-4) air conditioning compressor. This
com- is the freeze protection device in the system and
pressor may cycle on and off under normal air
senses refrigerant pressure on the suction side of the
conditioning demand. system. This switch is located on a standard
Schrader- -
All air conditioning systems that use the fixed
displacement R-4 compressor are referred to as
C. C.O.T. (Cycling Clutch, Orifice Tube) type sys-
tems. This is the same system that has been used on
all General Motors vehicles in the past several years.
The C.C.O.T. NG System
The Cycling Clutch Orifice Tube (C.C.O.T.)
refrigeration system is designed to cycle a compressor
on and off to maintain desired cooling and to prevent
evaporator freeze. Passenger compartment comfort is
maintained by the temperature lever on the controller.
Control of the refrigeration cycle (on and off
operation of the compressor) is done with a switch
which senses low-side pressure as an indicator of type
valve low-side fitting. During air temperatures
over 10°C
(50°F), the equalized pressures within the
charged
A/C system will close the contacts of the
pressure switch. When an air conditioning mode
(max, norm, bi-level, defrost) is selected, electrical
energy is supplied to the compressor clutch coil. AS
the compressor reduces the evaporator pressure
to
approximately 175 kPa (25 psi), the pressure switch
will open, de-energizing the compressor clutch.
As
the system equalizes and the pressure reaches approxl-
mately 315 kPa (46 psi), the pressure switch contacts
close, re-energizing the clutch coil. This cycling
coy
tinues and maintains average evaporator discharge air
temperature at approximately 1°C (33°F). Because of
this cycling, some slight increases and decreases of
engine speedlpower may be noticed under certain con-
ditions. This is normal as the system is designed
to
cycle to maintain desired cooling, thus preventing
evaporator freeze-up.

18-2 AIR CONDITIONING
SYSTEM GONIPONENE - FFUNCnIONAL
Compressor
All compressors are belt driven from the engine
crankshaft through the compressor clutch pulley. The
compressor pulley rotates without driving the com-
pressor shaft until an electromagnetic clutch coil is
energized. When voltage is applied to energize the
clutch coil, the clutch plate and hub assembly is
drawn rearward toward the pulley. The magnetic
force locks the clutch plate and pulley together as one
unit to drive the compressor shaft.
As the compressor shaft is driven, it compresses
the low-pressure refrigerant vapor from the evaporator
into a high-pressure, high-temperature vapor. Carried
with the refrigerant is the refrigerant oil which is used
to lubricate the compressor. Complete compressor
overhaul procedures can be found in Section
ID of the
General Service Manual.
Pressure Relief Valve
The compressor is equipped with a pressure
relief valve which is placed in the system as a safety
factor. Under certain conditions, the refrigerant on the
discharge side may exceed the designed operating
pressure. To prevent system damage, the valve is
designed to open automatically at approximately
3036
kPa (440 psi). Conditions that might cause this valve
to open (defective high pressure cut-off switch, inop-
erative electric cooling fan, etc.) should be corrected,
and the refrigerant oil and refrigerant should be
replaced as necessary.
A muffler is used on some refrigerant systems to
reduce compressor noises from high or low pressure
vibrations.
Condenser Gore
The condenser assembly in front of the radiator
is made up of coils which carry the refrigerant TO
cooling fins to provide rapid transfer of heat. The air
passing through the condenser cools the high-pressure
refrigerant vapor causing it to condense to a liquid.
Expansion (Orifice) Tube
The plastic expansion tube, with its mesh screen
and orifice, is located in the evaporator inlet pipe at
the liquid line connection. It provides a restriction to
the high-pressure liquid refrigerant in the liquid line,
metering the flow of refrigerant to the evaporator as a
low-pressure liquid. The expansion tube and orifice
are protected from contamination by filter screens on
both inlet and outlet sides. The tube is serviced only
as a replacement assembly.
When the engine is turned "OFF" with the
A/C
system operating, the refrigerant in the system will
flow from the high-pressure side of the expansion tube (orifice) to the low-pressure side until the pressure
is
equalized. This may be detected as a faint sound of
liquid flowing (hissing) for 30 to
60 seconds and is a
normal condition.
Evaporator Gore
The evaporator is a device which cools and
dehumidifies the air before it enters the car. High-
pressure liquid refrigerant flows through the expan-
sion tube (orifice) into the low-pressure area of the
evaporator. The heat in the air passing through the
evaporator core is transferred to the cooler surface of
the core, thereby cooling the air. As the process of
heat transfer from the air to the evaporator core sur-
face is taking place, any moisture (humidity) in the air
condenses on the outside surface of the evaporator
core and is drained off as water.
Accumulator
5-INTERNAL TUBE
2-REFRIGERANT 6-DESICCANT BAG
VAPOR INLET ASSEMBLY
7-FILTER ASSEMBLY
8-OIL BLEED HOLE
LOCATION IN TUBE
520004-1 8
Figure 1 Accumulator - Interior Parts
Connected to the evaporator outlet pipe, the
sealed accumulator assembly acts as a refrigerant stor-
ing container receiving vapor and some liquid and
refrigerant oil from the evaporator.
At the bottom of the accumulator is the desic-
cant which acts as a drying agent for moisture that
may have entered the system. An oil bleed hole is also
located near the bottom of the accumulator outlet pipe
to provide an oil return path to the compressor.

AIR CONDITIONING 1 B-3
A low-side pressure Schrader valve service fit-
ting is located near the top of the accumulator. A
similar Schrader fitting may be provided for mounting
the pressure cycling switch. It is not necessary to dis-
charge the system to replace the switch. The accumu-
lator is serviced only as a replacement assembly.
Heater Core
The heater core heats the air before it enters the
car. Engine coolant is circulated through the core to
heat the outside air passing over the fins of the core.
The core is functional at all times (no water valve) and
may be used to temper conditioned air in
A/C mode,
as well as heat or vent mode.
SYSTEM COMPONENTS --- CON"FOL
Controller
The operation of the A/C system is controlled by
the switches and the lever on the control head. The
compressor clutch and blower are connected electri-
cally to the control head by a wiring harness. The
blower circuit is open in the off mode and air flow is
provided by the four blower speeds available in the
remaining modes. Cooled and dehumidified air is
available in the max, normal, bi-level and defrost
modes.
Temperature is controlled by the position of the
temperature lever on the control head. A cable con-
nects this lever to the temperature door which controls
air flow through the heater core. As the temperature
lever is moved through its range of travel, a sliding
clip on the cable at the temperature valve connection
should assume a position assuring that the temperature
door will seat in both extreme positions. Temperature
door position is independent of mode selection. The
temperature cable attaches to the right side of the air
conditioning module. The temperature door on some
models is controlled electrically, thereby eliminating
the need for the temperature cable.
The electric engine cooling fan on some cars is
not part of the
A/C system; however, the fan is
operational any time the
A/C control is in Max.,
Norm, or Bi-Level modes. Some models provide for
engine cooling fan operation when the controller is in
the defrost mode. This added feature is part of the
A/C
controller function and is aimed at preventing exces-
sive compressor head temperatures. It also allows the
A/C system to function more efficiently. On some
models during road speed (above
35 mph) conditions
when air flow through the condenser coil is adequate
for efficient cooling, the engine cooling fan will be
turned off. The operation of the cooling fan is con-
trolled by the ECM through the cooling fan relay.
Complete wiring diagrams and diagnosis for the
AIC Electrical System are in Section 8A. Section 8A
also contains additional diagnostic information
regarding air flows and vacuum logic.
Vacuum Lines
Vacuum lines are molded to a connector which
is attached to a vacuum control switch on the control
head assembly.
In case of leakage or hose collapse, it will not be
necessary to replace the entire harness assembly.
Replacement can be made by cutting the hose and
inserting a plastic connector. If an entire hose must be
replaced, cut all hoses off at the connector and then
attach hoses directly to the control head vacuum
switch. (NOTE: The Fiero uses an electric motor to
control mode selection. Therefore, it will not have a
vacuum harness.
)
Vacuum Tank
During heavy acceleration, the vacuum supply
from the carburetor drops. A check valve in the vac-
uum tank maintains vacuum so that, under load condi-
tions, vacuum will be available for continuous use.
REWVS AND SWITCHES
High-Pressure Compresssr Gut-OFF Switch
The high-side, high-pressure cut-off switch in
the rear head of the compressor is a protective device
intended to prevent excessive compressor head pres-
sures and reduce the chance of refrigerant escape
through a safety relief valve. Normally closed, this
switch will open the circuit at a high-side pressure of
approximately 2700
kPa (430 psi 9 20 psi) and
reclose the circuit at approximately 1379 kPa (200 psi
9 50 psi).
Lsw-Pressure Cut-On Switch
Compressor protection is provided on some cars
by a low-pressure cut-off switch which will open in
the event of a low-charge condition. This switch can
be located in the liquid line or in the rear head of the
compressor. This switch will also keep the compres-
sor from running during cold weather.
Pressure eyesing Switch
The refrigeration cycle (on and off operation of
the compressor) is controlled by a switch which
senses the low-side pressure as an indicator of evapo-
rator temperature. The pressure cycling switch is the
freeze protection device in the system and senses
refrigerant pressure on the suction side of the system.
This switch is located on a standard Schrader-type
valve low-side fitting. This switch also provides com-
pressor cut-off during cold weather.
Additional compressor protection results from
the operating characteristics of the low-side pressure
cycling system. If a massive discharge occurs or the
orifice tube becomes plugged, low-side pressures
could be insufficient to close the contacts of the pres-
sure switch. In the event of a low charge, insufficient
cooling accompanied by rapid compressor clutch
cycling will be noticed at high air temperatures.

18-4 AIR CONDITIONING
If replacement of the pressure cycling switch is
necessary, it is important to note that this may be done
without removing the refrigerant charge.
A Schrader-
type valve is located in the pressure switch fitting.
During replacement of the pressure switch, a new
oiled O-ring must be installed and the switch assem-
bled to the specified torque of
6- 13 N*m (5- 10 lb. ft.).
Power Steering Gut-OH, or Anticipate
Switch
Engine idle quality on some cars is maintained
by cutting off the compressor (switch normally
closed) when high power steering loads are imposed.
On other cars the switch (normally open) provides a
signal to the ECM to allow engine control systems to
compensate for high-power steering loads.
Wide-Open Tkroale (WOT) Compressor
Cut-Out
Switch
A switch located on the throttle corltrols of some
carburetor equipped cars opens the circuit to the com-
pressor clutch during full throttle acceleration. The
switch activates a relay that controls the compressor
clutch. During full throttle acceleration
on cars
equipped with TBI or
Em, the TPS sends a signal to
the ECM, thereby controlling the compressor clutch.
Air Conditioning Time Delay Relay
This relay on some cars controls the current to
the entire air conditioning system and provides a short
delay of air conditioning operation upon start-up.
Constant Run Relay
Engine idle quality on some cars is maintained
by a "constant run" system (constant run relay) that
eliminates compressor cycling during engine idle for a
predetermined time after the vehicle has come to rest
from road speed.
If the idle period continues for an
extended time, the
A/C system may return to a con-
ventional C.C.O.T. mode for a short time to prevent
system freeze-up. The
A/C control relay and constant
run relays are both controlled by the Electronic Con-
trol Module (ECM) which determines operating con-
ditions by evaluating input from the distributor
(engine speed), vehicle speed sensor, air sensor and
A/C compressor "on" signal.
5-PRESSURE CYCLING 8-EXPANSION TUBE
SWITCH (ORIFICE)
6-DESSICANT BAG O-LIQUID LINE
7-OIL BLEED HOLE
10-PRESSURE RELIEF
VALVE
@ ee LOW PRESSURE LIQUID HIGH PRESSURE LIQUID LOW PRESURE VAPOR HIGH PRESSURE VAPOR
Figure 2 A/C System - Typical

AIR GONDlTlONlNG 1B-7
REFRIGERANT - 12
PRESSURE - TEMPERATURE
RELATIONSHIP
The table below indicates the pressure of Refri-
gerant - 12 at various temperatures. For in-
stance, a drum of Refrigerant at a temperature
of
&!OF (26.%C) will have a pressure of 84.1 PSI
(579.9 kPa). If it is heated to 129 F (51.%C), the
pressure will increase to 167.5 PSI (1154.9
kPa). It also can be used conversely to deter-
mine the temperature at which Refrigerant - 12 boils under various pressures. For example,
at a pressure of 30.1 PSI (207.5 kPa), Refriger-
ant - 12 boils at 32F ((PC).
O(ATM0SPHERIC PRESSURE)
2.4
4.5
Figure 7 A/C System Performance Test

18-14 AIR CONDITIONING
HANDLING OF REFRIGERANT LINES AND
FI-INGS
Tighten all tubing connections as shown in
torque chart (Figure 13). INSUFFICIENT OR
EXCESSIVE TORQUE WHEN TIGHTENING CAN
RESULT IN LOOSE JOINTS OR DEFORMED
JOINT PARTS. Either condition can result in refrig-
erant leakage.
All metal tubing lines should be free of dents or
kinks to prevent loss of system capacity due to line
restriction.
@ The flexible hose lines should never be bent to a
radius of less than four (4) times the diameter of
the hose.
@ The flexible hose lines should never be allowed
to come within a distance of
63.5mm (2-112") of
the exhaust manifold.
@ Flexible hose lines should be inspected regularly
for leaks or brittleness and replaced with new
lines if deterioration or leaking is found.
@ When disconnecting any fitting in the refrigera-
tion system, the system must first be discharged
of all Refrigerant- 12. Proceed very cautiously
regardless of gauge readings. Open very slowly,
keeping face and hands away so that no injury
can occur if there happens to be liquid
Refriger-
ant-12 in the line. If pressure is noticed when
fitting is loosened, allow it to bleed off as
described under DISCHARGING, ADDING
OIL, EVACUATING AND CHARGING PRO-
CEDURES FOR
A/C SYSTEMS.
@ In the event any refrigerant line is opened to the
atmosphere, it should be immediately capped or
taped to prevent entrance of moisture and dirt,
which can cause internal compressor wear or
plugged lines, in the condenser and evaporator
core and expansion (orifice) tubes or compressor
inlet screens.
@ The use of the proper wrenches when making
connections on O-ring fittings is important. The
opposing fitting should always be backed up
with a wrench to prevent distortion of connecting
lines or components. When connecting the flexi-
ble hose connections, it is important that the
swaged fitting and the flare nut, as well as the
coupling to which it is attached, be held at the
same time using three
(3) different wrenches to
prevent turning the fitting and damaging the
ground seat.
@ O-rings and seats must be in perfect condition. A
burr or piece of dirt may cause a refrigerant leak.
When replacing the O-ring, first dip it in clean
525 viscosity refrigeration oil.
MAINTAINING CHEMICAL STABILITY IN
THE
REFRIGERATION SYSTEM
The efficient operation and life of the air condi-
tioning system is dependent upon the chemical stabil-
ity of the refrigeration system. When foreign materials, such as
dirt, air, or moisture, contaminate
the refrigeration system, they will change the stability
of the Refrigerant-12 and 525 viscosity compressor
oil. They will also affect pressure-temperature rela-
tionship, reduce efficient operation and possibly cause
interior corrosion and abnormal wear of moving parts.
The following general practices should be
observed to insure chemical stability in the system:
1. Before disconnecting a refrigerant connection,
wipe away any dirt or oil at and near the connec-
tion to reduce the possibility of dirt entering the
system. Both sides of the connection should be
capped, plugged or taped as soon as possible to
prevent the entry of dirt, foreign material and
moisture.
2. Keep tools clean and dry. This includes the
manifold gauge set and replacement parts.
3. When adding 525 viscosity refrigerant oil (see
ADDING OIL in the DISCHARGING,
ADDING OIL, EVACUATING AND
CHARGING PROCEDURES FOR
AIC SYS-
TEMS, the transfer device and container should
be clean and dry to assure that refrigeration oil
remains as moisture-free as possible.
4. When it is necessary to "open" an
AIC system,
have everything needed ready and handy so that
as little time as possible will be required to per-
form the operation. Do not leave the
AIC system
open any longer than is necessary.
5. Any time the
A/C system has been "opened," it
should be properly evacuated before recharging
with Refrigerant- 12 according to the DIS-
CHARGING, ADDING OIL, EVACUATING
& CHARGING PROCEDURES FOR AIC
SYSTEMS.
All service parts are dehydrated and sealed
prior to shipping. They should remain sealed until just
prior to making connections. All parts should be at
room temperature before uncapping. (This prevents
condensation of moisture from the air entering the
system.) If, for any reason, caps are removed but the
connections are not made, parts should be resealed as
soon as possible.
DISCHARGING, ADDING OIL,
EVACUATING AND CHARGING
PROCEDURES FOR NC SYSTEMS
The refrigerant system may be discharged,
evacuated and charged using air conditioning service
charging station J-23500-01 or equivalent, or the
manifold and gauge set
5-23575-01 and 420ml (14
oz.) disposable cans of Refrigerant-12 (Figure 16).
Charging lines from the charging station or
manifold and gauge set require the use of gauge
adapters to connect to the system service fitting.
A
straight gauge adapter 5-5420 and a 90" angle gauge
adapter
5-9459 are available (see A/C Special Tools).
Always wear goggles and wrap a clean cloth
around fittings and connections when doing work that

AIR GONDlTlONlNG 1B-15
involves opening the refrigeration system. Always
work in a well ventilated area and avoid breathing any
refrigerant fumes. If liquid refrigerant comes into con-
tact with the eyes, injury may result.
@ Before removing and replacing any of the air
conditioning refrigeration lines or components,
the system must be completely discharged of
Refrigerant- 12.
@ Always use service valve and pressure gauge
sets during evacuation and charging procedures.
@ Always discharge system at low-side service fit-
ting and perform the entire evacuate and charg-
ing procedure through the low-side service
fitting.
@ Do not connect high-pressure line or any line to
the high-side
service fitting during discharging
and charging procedures.
CAUTION: Never remove a gauge line
from its adapter when line is connected
to
AIC system. Always remove the line
adapter from the service
fining to dis-
connect a line. Do not remove charging
hose at gauge set while
anached to ser-
vice low-side
fining. This will result in
complete discharge of system due to
the depressed Schrader valve in
service
low-side fining and may cause personal
injury due to escaping Refrigerant-12.
Discharging the NG System
In replacing any of the air conditioning refriger-
ation components, the system must be completely dis-
charged of Refrigerant- 12.
ALWAYS DISCHARGE SYSTEM AT
LOW-SIDE SERVICE FITTING.
1. With ignition turned "OFF," remove protective
cap from LOW-SIDE service fitting (on most
models) on Accumulator and connect charging
station
J-23500-01 or equivalent gauge set. If
charging station J-23500-01 or equivalent is not
being used, discharge system by slowly con-
necting a gauge hose to low-side
sewice fitting
on accumulator and discharging into oil bottle
(Figure 15). As hose is slowly tightened down
onto Schrader valve, Refrigerant-12 will begin
to discharge from the system into the container.
If no discharge occurs, check for missing or
defective Schrader depressor in hose fitting.
2. With the low-side of system fully discharged,
check high-side system fitting (on liquid line or
muffler) for remaining pressure.
3. If pressure is found, attempt to discharge high-
side using same procedure as used for low-side.
(This condition indicates a restriction on the
high-side and the cause must be diagnosed and
corrected before evacuating and charging the
system.)
4. When the system is completely discharged (no
vapor escaping with hose fully tightened down), measure, record
amount, and discard the col-
lected refrigerant oil. If the measured quantity is
15ml (112 fl. 02.) or more, this amount of new
525 viscosity refrigerant oil must be added to system, plus any quantity in removed parts
before system evacuation and charging with
Refrigerant-12 (see REFRIGERANT OIL DIS-
TRIBUTION for specific quantity of oil nor-
mally retained in removed parts).
Adding Oil to the Air Conditioning
Refrigerant System
ADDING OIL TO THE A/C SYSTEM should
take place AFTER discharge and BEFORE evacua-
tion procedures by removing the refrigeration suction
hose at the accumulator outlet pipe connection, pour-
ing the correct quantity of new refrigerant oil into the
hose or pipe and then properly reconnecting hose to
pipe (see REFRIGERANT OIL DISTRIBUTION for
specific quantity instructions).
1-USING J 5420 4-REFRIGERANT OIL BOTTLE UNCAPPED
TO ALLOW GAS
TO ESCAPE
2-GAGE HOSE 5-ACCUMULATOR
Figure 15 Discharging the A/C System Without
Charging Station
Refrigerant Oil Distribution
New 525 viscosity refrigerant oil must be added
to the system when components are replaced, as
follows:
A. All Compressors
@ If less than 30 ml(1 fl. oz.) is drained -
add 60 ml (2 fl. oz.).
@ If more than 30 ml(1 fl. oz.) is drained --
add same amount.

"18-16 AIR CONDITIONING
B . Accumulator dehydrator
@ Add 105 ml (3.5 fl. 02.) to new
accumulator
C. Evaporator
@ Add 90 ml (3 fl. oz.) oil
D. Condenser
@ Add 30 ml (1 fl. 02.) oil
Refrigerant oil loss due to a large leak
If the refrigerant charge is aburptly lost due to a
large refrigerant leak, approximately 90
ml (3 fl. oz.)
of refrigerant oil will be
carried out of the system sus-
pended in the refrigerant. Any failure that caused an
abrupt refrigerant discharge will experience this oil
loss. Failures that allow the refrigerant to seep or
bleed off over time do not experience this oil loss.
Upon replacement of a component which
caused a large refrigerant leak, add 90 ml(3
fl. oz.) of
new 525 viscosity refrigerant oil plus the required
amount of oil for the particular component (as out-
lined above).
Add the oil directly to the replaced component if
possible. If the oil cannot easily be added to the
replaced part, add the oil to the accumulator.
Evacuating and Charging the A/C System
If the system has been opened for any repair, or
the Refrigerant-12 charge lost, the system must be
evacuated prior to charging.
Evacuating and charging is a combined proce-
dure, and all gauge lines must be purged with R-12
prior to charging.
There are three evacuate and charge procedures.
1.
J 23500-01 Charging Station Method
2. Disposable Can Method 3. Drum Method
NOTICE: Under no circumstances should alco-
hol be used in the system in an attempt to remove
moisture. Damage to the system components
could occur.
Gauge Calibration
Prior to evacuation, check the low-pressure
gauge for proper calibration and determine if vacuum
system is operating properly.
With the gauge disconnected from the refrigera-
tion system, be sure that the pointer indicates to the
center of
"0". Lightly tap gauge a few times to be sure
pointer is not sticking. If necessary, calibrate as
follows:
1. Remove cover from gauge.
2. Holding gauge pointer adjusting screw firmly
with one hand, carefully force pointer in the
proper direction to position pointer at the
"0"
position. Tap gauge a few times to be sure
pointer is not sticking. Replace gauge cover.
Vacuum System Check
Before connecting vacuum pump to the A/C
system, run pump connected to the low-pressure
gauge to determine the vacuum pump capability. If
the vacuum system is unable to reach
7 1 1.2-736.6mm
(28"-29") or more vacuum, the system should be
checked for leaks. If no leaks are found, the vacuum
pump may require repair.
5-23580-81 OR EQUIVALENT CHARGING
STATION METHOD.
Follow charging instructions provided with the
5-23500-01 Charging Station or equivalent in use with
the following exceptions:
1. Do
not connect the high-pressure line to the air
conditioning system.
2. Keep the high-pressure valve on the charging
station closed at all times.
3.
Perform the entire evacuate and charge proce-
dure through the accumulator low-side pressure service fitting.
4. Following these procedures will prevent acci-
dental high-side vehicle system pressure being
subjected to the charging station in the event an
error is made in valve sequence during compres-
sor operation to pull in the Refrigerant-12
charge.
DISPOSABLE CAN OR REFRIGERANT
DRUM METHOD.
If the Refrigerant-12 drum is used, place it on a
scale and note the total weight before charging. Watch
the scale during charging to determine the amount of
R-12 used.
If disposable
420ml (14 ounce) R-12 cans are
used, close the tapping valve and then attach
can(s)
following instructions included with the tapping valve
or tapping manifold adapter.
1. Connect manifold gauge set 5-23575-01 as fol-
lows. Also see Figure 16.
a. Eow-pressure gauge to accumulator fit-
ting.
b. Gauge set center hosk to Refrigerant-12
source.
c. High-pressure gauge to vacuum pump.
2. To begin evacuation of the
A/C system with
manifold gauge set and vacuum pump as illus-
trated in Figure 16, slowly open
high- and low-
side gauge valves and begin vacuum pump oper-
ation. Pump the system until the low-side gauge
reaches 7 1
1.2-736.6mm (28"-29") vacuum.
Note that in all evacuation procedures, the spec-
ification of 7 1
1.2-736.6mm (28"-29") vacuum is
used. This specification can only be reached at
or near sea level. For each
304.8m (1,000 feet)
above sea level, specification should be lowered
by one inch vacuum. At
1524m (5,000 feet)
elevation, only
584.2-609.6mm (23"-24") of
vacuum is required.