
SCREW TYPE SEAL CANS
Ensure can tap is fully closed. Screw refrigerant can into can tap fitting until tight. This will pierce the can. Connect tap to center hose on
manifold gauge set. DO NOT open tap until ready to dispense R-12 into system.
CONNECTING LINES & FITTINGS
1. A new "O" ring should be used in all instances when connecting lines and fittings (dip "O" ring in clean refrigeration oil and make
certain it is not twisted during installation). Always use two wrenches to avoid twisting or distorting lines and fittings, tighten coupling
nuts securely.
2. Ford spring-coupling fittings require a special coupling tool (Motorcraft YT-1056) to open or close. Use the following procedure to
connect or disconnect the spring-coupling fitting.
Ford Spring-Coupling Fitting
1. Discharge system using approved refrigerant recovery/recycling equipment. Place proper end of tool over refrigerant line. Tool fits both
3/8" and 1/2" fittings. Push tool into fitting cage to release spring inside. Pull lines apart and remove tool.
2. Before connecting, check internal spring for damage. If necessary, pry spring out and replace it. Clean fittings and install new "O" rings.
Fig. 1: Assembling Ford Spring
-Coupling Fitting
PLACING SYSTEM IN OPERATION
After component replacement and/or system servicing has been completed and all connections have been made, proceed as follows:
1. Evacuate the system using a vacuum pump.
2. Charge the system with new R-12 (refrigerant) according to each individual vehicle as outlined in the GENERAL SERVICING article.
Also see Refrigerant Capacity in this Section.
3. Leak test the system, with particular attention to all new connections and components.
4. Make a performance test of the system. Never assume that a recharging has automatically corrected a problem.
COMPRESSOR REMOVAL INFORMATION - ISOLATION METHOD
On systems which have compressors equipped with stem-type service valves (Tecumseh), it is possible to isolate the compressor for removal.
Isolating
Turn both high and low pressure manual valves to extreme clockwise (front seat) position. Loosen cap on high pressure manual valve
connection to compressor and allow gas to escape until compressor is relieved of pressure.
COMPRESSOR REMOVAL INFORMATION-DISCHARGE METHOD
This procedure is to be used on vehicles which have compressor equipped with Schrader service valves. In these cases, the compressor cannot
be isolated and the system must be discharged, using approved refrigerant recovery/recycling equipment, prior to compressor removal. WARNING:DO NOT open high side hand valve while air conditioning system is in operation. T his high pressure
could rupture can or fitting at safety can valve, resulting in dam age and personal injury.
CAUT ION: Use ONLY "O" rings designed for these Ford fittings (Motorcraft YF-982). Norm al refrigerant "O" rings
will NOT seal.
Copyr ight 2009 Mitchell Repair Information Company, LLC. All Rights Reserved.
Article GUID: A00039191
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1991 AIR CONDIT IONING & HEAT
MANUAL A/C
A/C SYSTEM SPECIFICATIONS
SPECIFICATIONS
DESCRIPTION
This A/C-heater system is fully integrated to provide cooling, heating and ventilation with either fresh or recirculated air. A/C system is
expansion valve type. Interior air temperature is controlled by cycling the compressor on and off at different rates. A/C compressor is protected
by a low pressure switch, which stops compressor operation when refrigerant pressure is too low. Compressor operation is cut when throttle is
wide open to improve driveability.
The primary system components are compressor, receiver-drier, evaporator, low pressure switch, thermostatic switch, thermostatic expansion
valve, A/C control module, refrigerant lines and air ducts. See Fig. 1
and Fig. 2 . The heater core is continuously supplied with coolant. To
control temperature, air goes through and/or around heater core by way of temperature blend door.
Fig. 1: Identifying A/C System Components
Courtesy of FORD MOTOR CO. 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.
ApplicationSpecification
Compressor TypeNippondenso 10-Cylinder
Refrigerant (R-12) Capacity25 ozs.
System Oil Capacity10 ozs.
Compressor Belt Deflection
New9/32-11/32" (8-9 mm)
Used11/32-7/16" (9-11 mm)
System Operating Pressure (1)
Low Side19-25 psi (1.3-1.7 kg/cm2 )
High Side199-220 psi (13.9-15.4
kg/cm
2 )
(1)When measured at 79°F (26°C).
Page 1 of 14 MITCHELL 1 ARTICLE - 1991 AIR CONDITIONING & HEAT MANUAL A/C
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Fig. 7: Fuse Panel Identification
Courtesy of FORD MOTOR CO.
Fuse Identification
1 - 15 Amp License Plate Light, Rear Side Marker Light, Front Parking Lights, Cluster and Tail Lights
2 - 15 Amp Horn, Brakelights, High-Mount Brakelight
3 - 15 Amp (1988-89) Safety Belt Warning, Turn & Hazard Warning Flasher Lights, Radio, Trunk Light, Ignition Key Reminder Buzzer
15 Amp (1990-93) Safety Belt Warning, Turn & Hazard Warning Flasher Lights, Ignition Key Reminder Buzzer
4 - 15 Amp Audio System, Cigarette Lighter, Remote Control Mirror
5 - 15 Amp Rear Wiper/Washer, Daytime Running Light System (Canada)
6 - 15 Amp Heater & Air Conditioner
7 - 20 Amp Heater & Air Conditioner, Cooling Fan System
8 - 10 Amp (1988-89) Interior Courtesy Lights
10 Amp (1990-93) R a d io , In t e r io r C o u r t e sy Ligh t s, Lu gga ge C o mp a r t me n t Ligh t
9 - 15 Amp (1988-89) Front Wiper/Washer
15 Amp (1990-93) Front Wiper/Washer, Shift-Lock System (ATX), Engine Control System
10 - 10 Amp Charging System, Emission Control System
11 - 10 Amp (1988-90) Safety Belt Warning, Turn & Hazard Warning Flasher Lights, Back-Up Lights, Instrument Cluster, Warning
Lights,
10 Amp (1991-93) Safety Belt Warning, Turn & Hazard Warning Flasher Lights, Back-Up Lights, Instrument Cluster, Warning Lights,
Shift-Lock System
12 - 15 Amp Rear Window Defroster
13 - Not Used (1988-89) Spare
30 Amp (1990-93) Passive Restraint System (Automatic Seat Belt)
In-Line Fuse Identification
15 Amp (1990-93) Condenser Fan Motor (A/T Models Only)
10 Amp (1990-93) A/C System (located on left side of heater case)
FUSIBLE LINK BLOCK IDENTIFICATION
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Fig. 8: Underhood Fusible Link Block Identification
Courtesy of FORD MOTOR CO.
Fusible Link Identification
A - Brown (PTC) (1988-89 Carburetor) EFE Carburetor Heater
Brown (EGI) (1989-93 EFI) EFI System (1989-92), EGI-EFI System (1993)
B - Red (Main) Back-Up, Interior & Parking Lights, Brakelights, Taillights, Horn, Luggage Compartment Light, Turn Signal & Hazard
F l a sh e r Ligh t s, C l u st e r & Wa r n in g Ligh t s, R a d io , C iga r e t t e Ligh t e r , C h a r gin g & E missio n C o n t r o l S yst e ms, Wip e r / Wa sh e r S yst e ms,
A/C-Heater System, Cooling Fan System, Rear Window Defroster, Ignition & Starting Systems, Shift Lock System, Remote Control
Mirror, Ignition Key Reminder, Passive Restraint System (1990-93)
C - Brown (Head) Headlights, Daytime Running Lights, Starting & Charging System
Copyr ight 2009 Mitchell Repair Information Company, LLC. All Rights Reserved.
Article GUID: A00129179
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SERVICE INDICATOR & WARNING LIGHTS
1988-92 MAINT ENANCE Ford Motor Co. Service Indicator & Warning Lights
SERVICE INDICATOR & WARNING LIGHTS
Fig. 1: Identifying Dash Gauges & W arning Lights
Courtesy of FORD MOTOR CO.
CHECK ENGINE WARNING LIGHT
If functioning properly, the Check Engine warning light comes on when ignition switch is in the ON position and goes out after engine is
started. If light fails to glow with ignition on or remains on when engine is running, a malfunction exists in the electronic engine control
system. System needs to be checked and serviced.
CHARGING SYSTEM WARNING LIGHT
Light comes on when ignition switch is in the ON or START position and goes out after engine is started and alternator is charged. Light may
also glow when there is a heavy electrical load on the system. If light remains on after reducing electrical load, check electrical system.
OIL PRESSURE WARNING LIGHT
Light should come on briefly and go out after engine is started. If light remains on with engine running, oil pressure is low. Check oil level.
ENGINE COOLANT TEMPERATURE GAUGE
Gauge should register within the NORMAL band under regular operating conditions. If gauge rises into the HOT range, stop engine, allow it to
cool, and then check coolant level.
BRAKE WARNING LIGHT
The Brake light indicates one of 2 conditions: parking brake is engaged, or malfunction exists in the dual braking system. If functioning
properly, light should come on briefly with ignition switch in the ON position and then go out after engine is started and parking brake is
released. If light remains on, a malfunction is indicated. Service brake system.
Copyr ight 2009 Mitchell Repair Information Company, LLC. All Rights Reserved.
Article GUID: A00062872
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