air conditioning FORD FESTIVA 1991 Service Manual
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levels to proper level.
Removal (1.6L & 1.6L Turbo)
1. Relieve fuel pressure and discharge air conditioning system (if equipped). See FUEL PRESSURE RELEASE under REMOVAL &
INSTALLATION. Disconnect and remove battery, battery tray and battery tray support bracket.
2. Release wiring harness retaining straps from battery support tray. Disconnect windshield washer supply hose between fluid reservoir and
hood. Mark hinge locations and remove hood.
3. Disconnect intake air tube and wiring to ignition coil and vane airflow meter. Remove air cleaner/vane airflow meter assembly. Remove
air cleaner assembly support brackets. Disconnect intercooler hoses from turbocharger (if equipped).
4. Drain engine coolant and remove radiator. Disconnect accelerator cable, and remove retaining bracket from cam cover. Position cable to
one side.
5. Disconnect and plug fuel lines at fuel filter and pressure regulator. Disconnect power brake booster manifold vacuum hose from
manifold. Disconnect heater hoses at heater core tubes. Label and remove vacuum hoses located at throttle body.
6. For manual transaxle turbocharged vehicles, disconnect clutch cable and remove support bracket and cable from transmission. On non-
turbo vehicles, disconnect clutch slave hydraulic line. For automatic transaxle, remove transaxle cooler lines.
7. Disconnect starter wiring at starter. Remove harness from locating strap on bracket. Disconnect alternator wiring. Disconnect wiring
from engine coolant sensors located on rear of engine block. Remove ground connection at bracket on thermostat cover. Disconnect O2
sensor wire, main wiring harness connector, TPS connector (turbocharged only), knock sensor connector, distributor wiring and
transaxle wiring. Disconnect ground wire and strap at front of engine, and reinstall lifting eye.
8. Remove engine oil dipstick and retaining clip. Remove power steering pump from mounting bracket. Remove power steering pump
mounting bracket. With hoses attached, position pump aside. Remove upper air conditioning compressor retaining bolts (if equipped).
9. Raise vehicle on hoist. Drain engine oil and cooling system. On vehicles with air conditioning, remove lower air conditioning
compressor mounting bolts, and position compressor out of way.
10. Remove front wheels and tires. Remove front ball joints-to-ste e r in g kn u c kl e s r e t a in in g b o l t s. R e mo ve sp l a sh gu a r d s. Dr a in t ransmission
oil and remove half shafts from differential. Remove front exhaust pipe bracket located on lower side of engine. Disconnect front
exhaust pipe from exhaust manifold, or turbocharger (if equipped).
11. Remove frame support bar-to-engine support bolt. Loosen right control arm bolt and, pivot support bar downward. Disengage rubber
exhaust hangers located directly behind catalytic converter. Allow exhaust system to hang down 6 inches, and support system with
mechanic's wire. Unbolt shift linkage and stabilizer bar at transaxle. Remove nuts from front and rear engine mounts, and lower vehicle.
12. Attach chains onto lift eyes at ends of cylinder head, and support engine with hoist. Remove RH engine mount through bolt. Raise
engine off mounts and slightly pivot engine/transaxle assembly. Disconnect oil pressure sensor and route starter/alternator wiring
harness from engine. Carefully lift engine/transaxle assembly, turn assembly while raising to clear brake master cylinder, shift linkage
universal joint, radiator support and air conditioning lines (if equipped).
13. Remove intake manifold support bracket. Remove gusset plate(s) (if equipped). Remove starter. Remove transaxle-to-engine retaining
bolts. Identify bolts to ensure correct installation. Separate transaxle from engine. On manual transaxle, remove pressure plate, clutch
disc and flywheel. On automatic transaxle, remove flexplate.
Installation (1.6L & 1.6L Turbo)
1. Install transaxle to engine in reverse order of removal. Attach hoist to engine/transaxle assembly and position assembly in vehicle.
Before engine contacts mounts, route starter, alternator and oil pressure sensor wiring, and connect oil pressure sensor. Lower engine
until front mount seats on crossmember. Install through bolt on RH engine mount. DO NOT tighten bolt.
2. Remove hoist. Raise vehicle and support with jackstands. Align rear engine mount to crossmember, and install retaining nuts to front
and rear engine mounts. Tighten nuts to specification. See TORQUE SPECIFICATIONS
table at end of article.
3. On manual transaxles, connect shift coupling and stabilizer. Tighten to specification. On automatic transaxles, connect shift linkage and
oil cooler lines. Tighten linkage retaining bolt, shift cable pivot and oil cooler hose clamps to specification. Connect front exhaust pipe
to manifold (or turbocharger). Install exhaust pipe to support bracket. Tighten bolts to specification. Tighten manifold (or turbocharger)
to specification. Attach rubber exhaust hangers. Position cross brace. Tighten retaining nut and bolt and right control arm front bolt.
4. Install drive axles. Install ball joint retaining bolts and tighten to specification. Mount A/C Compressor to engine (if equipped). Tighten
lower retaining bolts to specification. Install splash guards. Install tire and wheel assemblies. Tighten retaining nuts to specification.
5. Lower vehicle. Install upper A/C compressor retaining bolts (if equipped). Tighten bolts to specification. Tighten RH engine mo u n t
through bolt to specification. Connect alternator wiring.
6. Position power steering pump bracket on stud. Lower pump into engine compartment. Install power steering pump bracket retaining
bolts and nut. Tighten to specification. Install power steering pump and belt. Tighten adjustment nut and pivot bolt to specification.
7. Install engine oil dipstick and retaining clip. Install ground strap and ground wire to cylinder head. Install clutch cable (if equipped).
Connect clutch hydraulic line if equipped with manual transaxle or naturally aspirated. Connect transmission electrical connectors.
Connect fuel lines to fuel filter and pressure regulator. Install intake air tube to throttle body.
8. Install intercooler hoses on turbocharged models. Install air cleaner assembly brackets. Install air cleaner assembly with airflow meter
attached. Install intake air tube. Install coil and airflow meter connectors. Connect coolant crankcase and air bypass hoses. Install
vacuum hoses as noted in disassembly.
9. Connect accelerator cable. Install retaining bracket. Install power brake booster hose. Remove speedometer cable from transaxle. Fill
transaxle to specification. See CAPACITIES in SERVICE & ADJUSTMENT SPECIFICATIONS article. Install speedometer cable.
Connect speedometer cable connector. Fill engine oil to capacity.
10. Install radiator/fan assembly. Tighten bracket retaining bolts to specification. Connect coolant hoses and fan electrical connector. Fill
coolant to specification.
11. Install hood and connect washer hose. Install battery tray support, battery tray, battery and battery hold-down. Connect battery
terminal. Evacuate and charge air conditioning system (if equipped). Road test vehicle and inspect for leaks.
INTAKE MANIFOLD
Removal (1.3L)
CAUT ION: DO NOT allow com pressor to hang by hoses. T ie up com pressor with m echanic's wire.
Page 2 of 19 MITCHELL 1 ARTICLE - ENGINE OVERHAUL 1991-92 FORD MOTOR CO. ENGINES 1.3L & 1.6L 4-Cylinder
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CLUTCH ENGAGE SWITCH (CES)
This switch is located on the manual transaxle and informs the ECA of transmission operating conditions. The ECA uses this data fo r id l e
speed control and canister purge valve operation.
CRANKSHAFT POSITION SENSOR (CPS) (FESTIVA)
This sensor is located in the distributor and sends engine RPM and crankshaft position data to the ECA. The ECA uses this data in calculating
fuel metering, ignition timing, idle speed control and canister purge valve operation.
CYLINDER IDENTIFICATION SENSOR (CID) (CAPRI)
This sensor is located in the distributor and provides crankshaft position data to the ECA. The ECA uses this data in calculating fuel metering
and ignition timing.
ELECTRICAL LOAD SWITCHES
Blower control, cooling fan, rear window defroster, air conditioning and headlight switches all send signals to the ECA. The ECA uses these
signals for idle speed control.
ENGINE COOLANT TEMPERATURE (ECT) SENSOR
This sensor is located in the intake manifold and sends coolant temperature data to the ECA. The ECA uses this data in calculating fuel
metering, idle speed control and canister purge valve operation.
EXHAUST GAS OXYGEN (EGO) SENSOR
This sensor is located in the exhaust manifold and senses oxygen concentration in the exhaust gas. The ECA uses this data in calculating fuel
metering, idle speed control and canister purge valve operation.
NEUTRAL SAFETY SWITCH (A/T)
This switch is located on the automatic transaxle and sends a signal to the ECA whenever the transaxle is in Neutral or Park ranges. The ECA
uses this signal in calculating fuel metering, idle speed control and canister purge valve operation.
POWER STEERING PRESSURE SWITCH (PSPS)
This switch is located on the power steering pump and sends data about power steering operation to the ECA. The ECA uses this data for idle
speed control.
THROTTLE POSITION SENSOR (TP)
This device is located on the throttle body and contains 2 switches. The Wide Open Throttle (WOT) Switch sends a signal to the ECA when
throttle valve opening is more than 70 degrees. The ECA uses this signal in calculating fuel metering.
The Idle Switch (IDL) sends a signal to the ECA when throttle valve opening is less than 1.5 degrees. The ECA uses this signal for idle speed
control and canister purge valve operation.
VANE AIRFLOW (VAF) METER
This sensor is located in the air cleaner housing and sends intake airflow data to the ECA. The ECA uses this data in calculating fuel metering.
VANE AIR TEMPERATURE (VAT) SENSOR
This sensor is located inside the vane airflow sensor and senses intake air temperature. The ECA uses this data in calculating fu el met erin g,
idle speed control and canister purge valve operation.
CEC OUTPUT SIGNALS
CANISTER PURGE (CANP) SOLENOID
See EMISSION SYSTEMS.
CHECK ENGINE LIGHT
See SELF-DIAGNOSTIC SYSTEM.
FUEL INJECTORS
See FUEL CONTROL.
IDLE SPEED CONTROL BY-PASS AIR (ISC-BPA) VALVE
See IDLE SPEED. NOTE:Vehicles are equipped with different com binations of com puter-controlled com ponents. Not all
com ponents listed below are used on every vehicle. For theory and operation of each output
com ponent, refer to indicated system .
Page 2 of 6 MITCHELL 1 ARTICLE - E - THEORY/OPERATION 1991 ENGINE PERFORMANCE Ford/Mercury Theory & Operation
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GENERAL INFORMATION
Com m only Used Abbreviations
* PLEASE READ THIS FIRST *
"A"
A
Amperes
ABS
Anti-Lock Brakes
ABRS
Air Bag Restraint System
AC
Alternating Current
A/C
Air Conditioning
ACCS
A/C Cycling Switch
ACCUM
Accumulator
ACCY
Accessory
ACT
Air Charge Temperature Sensor
ADJ
Adjust or Adjustable
ADV
Advance
AFS
Airflow Sensor
AI
Air Injection
AIR or A.I.R.
Air Injection Reactor
AIS
Air Injection System
Alt.
Alternator or Altitude
Amp./amp/amps
Ampere NOTE:T his article is intended for general inform ation purposes only. T his inform ation m ay not apply to all
m akes and m odels. Not all abbreviations are covered as m anufacturers add new ones every day.
Page 1 of 15 MITCHELL 1 ARTICLE - GENERAL INFORMATION Commonly Used Abbreviations
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AIR CONDITIONING & HEAT
AIR CONDITIONING TROUBLE SHOOTING
BASIC AIR CONDITIONING TROUBLE SHOOTING CHART
HEATER SYSTEM TROUBLE SHOOTING
BASIC HEATER SYSTEM TROUBLE SHOOTING CHART
Broken lead or loose soldered connectionsRepair wire or wire
connections as necessary
Solenoid Plunger Vibrates When Switch is Engaged
Weak batteryCharge or replace battery as
necessary
Solenoid contacts corrodedClean contacts or replace
solenoid
Faulty wiringCheck all wiring leading to
solenoid
Broken connections inside switch coverRepair connections or replace
solenoid
Open hold-in wiresolenoid
Low Current Draw
Worn brushes or weak brush springsReplace brushes or brush
springs as necessary
High Pitched Whine During Cranking Before Engine Fires but Engine Fires and Cranks Normally
Distance too great between starter pinion and flywheelAlign starter or check that
correct starter and flywheel are
being used
High Pitched Whine After Engine Fires With Key released. Engine Fires and Cranks Normally
Distance too small between starter pinion and flywheelFlywheel runout contributes to
the intermittent nature
WARNING:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITIONPOSSIBLE CAUSE
Compressor Not WorkingCompressor clutch circuit open.
.....Compressor clutch coil inoperative.
.....Poor clutch ground connection.
.....Fan belts loose.
.....Thermostatic switch inoperative.
.....Thermostatic switch not adjusted.
.....Ambient temperature switch open.
.....Superheat fuse blown.
Excessive Noise or VibrationMissing or loose mounting bolts.
.....Bad idler pulley bearings.
.....Fan belts not tightened correctly.
.....Compressor clutch contacting body.
.....Excessive system pressure.
.....Compressor oil level low.
.....Damaged clutch bearings.
.....Damaged reed valves.
.....Damaged compressor.
In su fficien t o r No Co o l in g; Co mp resso r
WorkingExpansion valve inoperative.
.....Heater control valve stuck open.
.....Low system pressure.
.....Blocked condenser fins.
.....Blocked evaporator fins.
.....Vacuum system leak.
.....Vacuum motors inoperative.
.....Control cables improperly adjusted.
.....Restricted air inlet.
.....Mode doors binding.
.....Blower motor inoperative.
.....Temperature above system capacity.
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to DIAGNOST IC,
or T EST ING articles available in the section(s) you are accessing.
Page 6 of 36 MITCHELL 1 ARTICLE - GENERAL INFORMATION Trouble Shooting - Basic Procedures
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1991 GENERAL SERVICING
A/C Com pressor Refrigerant Oil Checking
ISOLATING COMPRESSOR
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
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.
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). NOTE:Only com pressors with stem -type service valves can be isolated.
NOTE:Recent findings by the EPA indicate that refrigerant is harm ful to the earth's protective Ozone layer.
When discharging refrigerant, DO NOT allow refrigerant to enter the atm osphere. If available, use
refrigerant recovery/recycle system s when discharging system . Always follow m anufacturer's
instructions.
NOTE:Air conditioning system s will not norm ally need addition of refrigerant oil unless definite oil loss has
occurred due to ruptured lines, leaking com pressor seals, com pressor overhaul or com ponent
replacem ent.
Page 1 of 4 MITCHELL 1 ARTICLE - 1991 GENERAL SERVICING A/C Compressor Refrigerant Oil Checking
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GENERAL SERVICING
1991 Ford Com pressor Overhaul
REMOVAL & INSTALLATION
FORD FS-6 6-CYL CLUTCH ASSEMBLY
Removal
1. Using Spanner (T70P-4067-A), remove compressor shaft nut. Thread Hub Remover (T80L-19703-B) into clutch plate. Tighten center
bolt in hub remover to remove clutch plate and shims.
2. Remove snap ring. Remove pulley assembly from compressor. If assembly cannot be easily removed, place Shaft Protector (T80L-
19703-G) over shaft. Using Puller (D81P-19703-B), remove pulley assembly. Remove clutch coil retaining snap ring. Remove clutch
coil.
3. If bearing replacement is required, place pulley on Support (T80L-19703-E). Drive bearing from pulley using Bearing Remover (T80L-
19703-J).
Installation
1. If bearing is to be installed, place pulley on support. Using Bearing Installer (T80L-19703-C), drive bearing into pulley. Stake pulley in
4 places to retain bearing.
2. Install clutch coil on compressor so locating pin on compressor engages with hole in clutch coil. Install snap ring. Using hammer and
Pulley Installer (T80L-19703-J), tap pulley assembly on compressor.
3. Install snap ring with beveled side away from compressor. Using Clutch Plate Installer (T80L-19703-F), install clutch plate and shims.
Install and tighten compressor shaft nut to 10-14 ft. lbs. (14-19 N.m).
4. Using feeler gauge, measure air gap between clutch plate and pulley surface in 3 locations around pulley. Rotate pulley 180 degrees and
recheck clearance. Proper clearance is .021-.036" (.05-.91 mm). Adjust shim thickness to obtain correct clearance.
FORD FS-6 6-CYL SHAFT SEAL
Removal
1. Discharge system using approved refrigerant recovery/recycling equipment and remove compressor. Drain oil from compressor and
record amount for reassembly.
2. Remove clutch assembly. See FORD FS-6 6-CYL CLUTCH ASSEMBLY R & I in this article. Ensure compressor outer surface is clean.
Attach compressor on Clamp & Holding Fixture (T81P-19623-D). Place fixture in vise.
3. Using Key Remover (T81P-19623-NH), remove key from compressor shaft. Remove front head-to-compressor retaining bolts. Remove
front head. Front valve plate assembly, inlet reed valve and shaft seal assembly come off with front head. See Fig. 1
.
4. Remove dowel pins from front head. Lift inlet reed valve assembly from front head. Using Valve Plate Remover (T81P-19623-B),
remove front valve plate assembly from front head. Remove shaft seal assembly and felt seal from front head.
5. Place front head on cardboard. Using hammer and Shaft Seal Seat Remover (T81P-19623-OH), drive shaft seal seat from front head.
Clean components with solvent. CAUT ION: When discharging air conditioning system , use only approved refrigerant recovery/recycling
equipm ent. Make every attem pt to avoid discharging refrigerant into the atm osphere.
CAUT ION: DO NOT drive clutch plate on com pressor. Use clutch plate installer to prevent dam aging
com pressor. DO NOT tighten com pressor shaft nut with air tools.
Page 1 of 7 MITCHELL 1 ARTICLE - GENERAL SERVICING 1991 Ford Compressor Overhaul
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A/C COMPRESSOR SERVICING
1991 GENERAL SERVICING Com pressor Service
ISOLATING COMPRESSOR
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
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.
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
. CAUT ION: When discharging air conditioning system , use only approved refrigerant recovery/recycling
equipm ent. Make every attem pt to avoid discharging refrigerant into the atm osphere.
NOTE:Only com pressors with stem -type service valves can be isolated.
CAUT ION: When discharging air conditioning system , use only approved refrigerant recovery/recycling
equipm ent. Make every attem pt to avoid discharging refrigerant into the atm osphere.
NOTE:Air conditioning system s will not norm ally need addition of refrigerant oil unless definite oil loss has
occurred due to ruptured lines, leaking com pressor seals, com pressor overhaul or com ponent
replacem ent.
Page 1 of 18 MITCHELL 1 ARTICLE - A/C COMPRESSOR SERVICING 1991 GENERAL SERVICING Compressor Service
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1991-92 AIR CONDIT IONING & HEAT ING
A/C System General Servicing
HANDLING/SAFETY PRECAUTIONS
1. Always work in a well-ventilated, clean area. Refrigerant R-134a is colorless and is invisible as a gas. Refrigerant (R-12 or R-134a) is
heavier than oxygen and will displace oxygen in a confined area. Avoid breathing refrigerant vapors. Exposure may irritate eyes, nose
and throat.
2. The system's high pressure can cause severe injury to eyes and skin if a hose were to burst. Always wear eye protection when working
around A/C system and refrigerant. If necessary, wear rubber gloves or other protective clothing.
3. Refrigerant evaporates quickly when exposed to atmosphere, freezing anything it contacts. If liquid refrigerant contacts eyes or skin, DO
NOT rub eyes or skin. Immediately flush affected area with cool water for 15 minutes and consult a doctor or hospital.
4. Never use R-134a in combination with compressed air for leak testing. Pressurized R-134a in the presence of oxygen (air concentrations
greater than 60% by volume) may form a combustible mixture. DO NOT introduce compressed air into R-134a containers (full or
empty), A/C system components or service equipment.
5. DO NOT expose A/C system components to high temperatures, steam cleaning for example, as excessive heat will cause
refrigerant/system pressure to increase. Never expose refrigerant directly to open flame. If refrigerant needs to be warmed, place bottom
of refrigerant tank in warm water. Water temperature MUST NOT exceed 125°F (52°C).
6. Use care when handling refrigerant containers. DO NOT drop, strike, puncture or incinerate containers. Use Department Of
Transportation (DOT) approved, DOT 4BW or DOT 4BA, refrigerant containers.
7. Never overfill refrigerant containers. The safe filling level of a refrigerant container MUST NOT exceed 60% of the container's gross
weight rating. Store refrigerant containers at temperature less than 125°F (52°C).
8. R-12 refrigerant (Freon) will be sold and stored in White containers, while R-134a refrigerant will be sold and stored in 30- or 50-
pound Light Blue containers.
9. R-12 and R-134a refrigerants must never be mixed, as their desiccants and lubricants are not compatible. If the refrigerants are mixed,
system cross-contamination or A/C system component failure may occur. Always use separate servicing and refrigerant
recovery/recycling equipment.
10. Follow equipment manufacturer instructions of all service equipment to be used. The Material Safety Data Sheet (MSDS), provided by
refrigerant manufacturer/suppliers, contains valuable information regarding the safe handling of R-12 or R-134a refrigerants.
IDENTIFYING R-134A SYSTEMS & COMPONENTS
To prevent refrigerant cross-contamination, use following methods to identify R-134a based systems and components.
Fittings & "O" Rings
All R-134a based A/C systems use 1/2" - 16 ACME threaded fittings (identifiable by square threads) and quick-connect service couplings. See
Fig. 1
. Besides the use of these fittings, most manufacturers will use Green colored "O" rings in R-134a systems. CAUT ION: When discharging air conditioning system , use only approved refrigerant recovery/recycling
equipm ent. Make every attem pt to avoid discharging refrigerant into the atm osphere.
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Fig. 1: Identifying R
-134a Fittings & Quick Connect Service Couplings
Courtesy of AUDI OF AMERICA, INC.
Underhood A/C Specification Labels
Most R-134a based systems will be identified through the use of Green or Light Blue underhood labels, or with R-134a refrigerant clearly
printed on labels. See Fig. 2 . Some manufacturers will identify R-12 based systems with White, Red, Silver or Gold underhood labels. Before
servicing an A/C system, always determine which refrigerant is being used.
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Fig. 2: Underhood A/C Specification Labels (Typical)
Courtesy of NISSAN MOTOR CO., U.S.A.
Other Means Of Identification
Refrigerant R-134a, when viewed through a sight glass, may have a "milky" appearance due to the mixture of refrigerant and lubricating oil. As
the refrigerant and oil DO NOT exhibit a "clear" sight glass on a properly charged A/C system, R-134a systems have no sight glass.
Audi, Mercedes-Benz and Volkswagen use Green bands/labels on condenser, refrigerant lines, receiver-drier and expansion valve. Lexus A/C
system hoses and line connectors have a groove, a White line and "R-134a" marked on them. See Fig. 3
.
Fig. 3: Identifying R
-134a Hose & Line Connectors (Lexus)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
REFRIGERANT OILS
Refrigerant R-12 based systems use mineral oil, while R-134a systems use synthetic/Polyalkylene Glycol (PAG) oils. Using a mineral oil based
lubricant with R-134a will result in A/C compressor failure due to lack of proper lubrication.
Use ONLY specified oil for the appropriate system and A/C compressor. Always check the underhood A/C specification label or A/C
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