HEATER A N D AIR C O N D IT I O N I N G
1A-35
The compressor discharge pressure switch also performs
the function of the ambient switch as the pressure at the
switch varies directly with ambient temperatures. The
compressor should
not
run below 25°F. ambient or 37 psi
at the switch. The compressor should run in A/C modes
above 45°F. ambient or 42 psi at the switch.
The switch interacts with other switches so that in an
A/C system where the compressor will
not
operate above
45° ambient the following components should be checked
for continuity:
1. Compressor discharge pressure switch.
2. Master switch (on control head).
If both switches show proper continuity, check the
harness for shorts or improper ground conditions.
G Models
This low refrigerant charge protector system consists of a
superheat shutoff switch located in the rear head of the
compressor, connected in series by an electrical lead to a
thermal fuse.
During normal air conditioning system operating
conditions, current flows through the air conditioner
switch, the ambient switch, and through the thermal fuse
link to the clutch coil to actuate the compressor clutch.
Should a partial or total loss of refrigerant in the system
cause the superheat switch to sense low system pressure
and a high suction gas temperature, the superheat switch
contacts will close. When the contacts close, current flows
to energize the resistance type heater in the thermal fuse.
The resultant heat warms the fuse link to its specific melt
temperature, thus opening the circuit to the compressor
clutch coil. Compressor operation ceases and compressor
damage due to a loss of refrigerant charge is prevented.
The cause of the refrigerant loss must be corrected
and
the system charged prior to replacing the thermal fuse.
The superheat switch does not have to be replaced when
it cycles and is reusable unless it is determined that the
switch is faulty.
CHEMICAL INGREDIENTS OF AN
AIR CONDITIONING SYSTEM
All systems involve metals, refrigerant, and oil which are
basic and essential. The desiccant, or dehydrating agent,
and another chemical ingredient, synthetic rubber,
makes it even more complex.
All of these ingredients have chemical properties which
are entirely different from each of the others. By proper
selection of the ingredients and controlled processes in
manufacture, plus careful servicing procedures, they can
be combined so that they provide many years of
satisfactory and trouble-free operation.
Only one undesirable element added or allowed to enter
the system can start a chain of chemical reactions which
upsets stability and interferes with the operation of the
unit.
Chemical Instability and Refrigerant
System Failures
A sealed refrigerating system is a complex physical-
chemical combination which is designed for stability
within certain operating limits. If these limits are
exceeded, many physical and chemical reactions occur to
the system. Since the results of these reactions within the
system cannot be easily removed, they build up into a
constantly accelerating vicious circle to eventually fail
the system.
Metals
In most cases, metals contribute to the decomposition of
R-12 and oil in varying amounts. All metals are attacked
by acids.
Each of the metals in common use in a system has been
selected for a specific reason; heat conductivity,
durability, strength, and chemical composition.
Under favorable conditions, the amount of decomposi
tion of Refrigerant-12 and oil produced by these metals
is negligible. If undersirable substances are added and
the temperature is increased, the rate of decomposition
and the production of harmful acids increases
proportionally.
Refrigerant
The chemical properties of refrigerants are very
important factors in the stability of a system since the
refrigerant penetrates to every part of the unit.
Among the many desirable properties of R-12, is its
stability under operating conditions. While more stable
than the other refrigerants under the same conditions, it
can be caused to form harmful acids which will
eventually fail the system.
Oil
Oil is the most complex of all organic chemicals. Its
stability in a refrigerating system is dependent upon the
source of crude oil and its method of refining. A good
refrigeration oil must be free of sludge, gum-forming
substances and impurities such as sulphur. It must be
stabilized to resist oxidation and must have a high
degree of resistance to carbonization.
The chemical properties of the lubricating oil form
another very important consideration in the chemical
stability within the system. Like the refrigerant, it travels
to every part of the system.
The factory obtains the finest oils which have been
refined from the most desirable crudes. It is reprocessed
at the factory before it is charged into a system or
poured into a container for resale. Its viscosity and flash
point are checked and it is forced through many sheets
of filtering paper.
Even the containers in which it is poured for resale are
processed. It is the cleanest, dryest, and purest oil that is
humanly possible to make. Leaving the container
LIGHT DUTY TRUCK SERVICE MANUAL
Содержание Light Duty Truck 1973
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Страница 39: ...HEATER AND AIR CONDITIONING 1A 13 Fig 14 Heater Wiring Diagrams LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 53: ...HEATER AND AIR CONDITIONING 1A 27 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 115: ...LIGHT DUTY TRUCK SERVICE M A N U A L HEATER AND AIR CONDITIONING 1A 89...
Страница 123: ...BODY 1B 3 Fig 6 Typical 06 Van LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 149: ...BODY 1B 29 Fig 84 Body Mounting 06 Fig 85 Body Mounting 14 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 171: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 2 Frame Horizontal Checking Typical FRAME 2 3...
Страница 173: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 4 10 30 Series Truck Frame FRAME 2 5...
Страница 174: ...2 6 FRAME LIGHT DUTY TRUCK SERVICE MANUAL Fig 5 Underbody Reference Points G Van...
Страница 177: ...LIGHT DUTY TRUCK SERVICE MANUAL G 10 20 C 10 P 10 30 Fig 2 Front Suspension C P K Typical FRONT SUSPENSION 3 3...
Страница 185: ...FRONT SUSPENSION 3 11 Fig 16 Toe out on Turns LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 229: ...REAR SUSPENSION AND DRIVELINE 4 5 Fig 13 Rear Spring Installation C K Models LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 310: ...5 44 BRAKES C MODELS G MODELS P MODELS Fig 77 Parking Brake System LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 351: ...ENGINE 6 15 Fig ID Sectional View of Eight Cylinder Engine LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 377: ...ENG IN E 6 41 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 378: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 37L K Series Engine Front Mount 6 42 ENG INE...
Страница 379: ...E N G IN E 6 43 FRONT MOUNT REAR MOUNT Fig 38L G Series Engine Mounts LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 400: ...6 6 4 ENG INE LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 402: ...6 6 6 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 403: ...E NG IN E 6 67 Fig 36V C Series Engine Mounts LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 423: ...EN G IN E C OOLING 6K 13 Fig 16 Overheating Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 424: ...6 K 1 4 ENG INE COOLING Fig 17 Coolant Loss Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 455: ...ENGINE FUEL 6M 31 Fig K13 Accelerator Controls P30 42 454 Engine LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 456: ...6M 32 ENGINE FUEL Fig K15 Accelerator Controls G Van L 6 LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 506: ...CEC PLUNGER IS EXTENDED Fig lid Vacuum Advance Diagram Six Cylinder Engine 6T 14 EMISSION CONTROL SYSTEMS...
Страница 512: ...Fig 18e Vacuum Advance Diagram V8 Engine...
Страница 515: ...EMISSION CONTROL SYSTEMS 6T 23 Fig If Six Cylinder A I R System LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 516: ...6 T 2 4 E M IS S IO N CONTROL SYSTEMS LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 517: ...E M IS S IO N C O N TR O L SYSTEM S 6T 25 Fig 4f Diverter Valve Vent Valve LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 540: ...6 Y 1 2 ENGINE ELECTRICAL Fig 16b Battery Installation C K Series LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 572: ...6Y 44 ENGINE ELECTRICAL Fig 25i V 8 Spark Plug Wire Installation LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 592: ...7M 2 CLUTCHES MANUAL TRANSMISSIONS VIEW B Fig la Clutch Linkage Assy C K Models LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 593: ...CLUTCHES MANUAL TRANSMISSIONS 7M 3 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 594: ...7M 4 CLUTCHES MANUAL TRANSMISSIONS Fig lc Clutch Linkage Assy P Models LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 598: ...7M 8 CLUTCHES MANUAL TRANSMISSIONS LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 656: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 19M Drive Range Low First Gear Typical 7A 14 AUTOMATIC T R A N S M IS S IO N...
Страница 662: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 22M LI Range Manual First Gear Typical 7A 20 AUTOMATIC TRANSMISSION...
Страница 668: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 25M Reverse Range Typical 7A 26 AUTOMATIC T R A N S M IS S IO N...
Страница 739: ...FUEL TANKS AND EXHAUST 8 9 Fig 15 Filler Neck and Vent Hose Van LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 740: ...8 10 FUEL TANKS AND EXHAUST Fig 16 Fuel Feed and Return Pipes Front C K LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 743: ...FUEL TANKS AND EXHAUST 8 13 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 744: ...8 14 FUEL TANKS AND EXHAUST LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 746: ...8 16 FUEL TANKS AND EXHAUST Fig 2 5 Fuel Feed Pipe Front P 105 4 2 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 760: ...8 30 FUEL TANKS AND EXHAUST Fig 40 Exhaust Pipe P Models LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 761: ...FUEL TANKS AND EXHAUST 8 31 LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 781: ...STEERING 9 15 OIL PRESSURE OIL RETURN PORT VALVE BODY Fig 21 Left Turn Position LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 832: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 106 Power Steering Pump Mounting Typical 9 66 STEERING...
Страница 833: ...PUMP ASSEMBLY STEERING GEAR TYPICAL SMALL V8 TYPICAL LARGE V8 STEERING 9 67...
Страница 860: ...9 94 STEERING LEAKAGE AREAS Fig 133 Power Steering Gear Leakage LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 861: ...STEERING 9 95 Fig 134 Power Steering Pump Leakage LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 886: ...11 10 CHASSIS SHEET METAL LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 891: ...ELECTRICAL BODY AND CHASSIS 12 5 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 897: ...ELECTRICAL BODY AND CHASSIS 12 11 Fig 14 Instrum ent Cluster Assembly C K Models LIGHT DUTY TRUCK SERVICE MANUAL...
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