GENERAL PROCEDURES
Fittings
—R-Clip
Disconnect WARNING: Do not smoke or carry lighted tobacco or open flame of any type when
working on or near any fuel- related components. Highly flammable mixtures are always present
and may be ignited, resulting in possible personal injury.
WARNING: Fuel in the fuel system remains under high pressure even when the engine is
not running. Before servicing or disconnecting any of the fuel lines or fuel system components,
the fuel system pressure must be relieved to prevent accidental spraying of fuel, causing
possible personal injury or a fire hazard.
CAUTION: Do not use any tools. The use of tools may cause a deformity in the clip
components which may cause fuel leaks.
1. Relieve the fuel system pressure. For additional information, refer to Pressure Relief in this
section.
2. Remove the shipping tab by bending.
3. Spread the R- clip legs and push the clip into the fitting.
SECTION 310-
00: Fuel System — General Information 2003 Mustang Workshop Manual Material
Item Specification
SAE 5W-
20 Super Premium
Synthetic Blend Motor Oil
XO- 5W20- QSP or equivalent WSS-
M2C153-
H Klj . 1 ba
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4. Separate the fitting from the tube.
Connect 1. NOTE: Apply a light coat of clean engine oil.
Clean and inspect the fitting and the tube for damage.
2. Insert the R- clip into the fitting.
3. Insert the tube in the fitting and push together until a click is heard. Klj . 2 ba
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DESCRIPTION AND OPERATION
Climate Control System
WARNING: To avoid accidental deployment and possible injury, the air bag system
backup power supply must be depleted before repairing any climate control components. To
deplete the backup power supply, disconnect the battery ground cable and wait one minute.
Failure to follow these instructions may result in personal injury.
WARNING: Carbon monoxide is colorless, odorless and dangerous. If it is necessary to
operate the engine with the vehicle in a closed area such as a garage, always use an exhaust
collector to vent the exhaust gases outside the closed area.
WARNING: R- 134a is classified as a safe refrigerant, but misuse can make it dangerous.
The following precautions must be observed:
zAlways wear safety goggles when repairing an air conditioning system.
z Avoid contact with liquid refrigerant R- 134a. R-134a vaporizes at approximately - 25°C (-
13°F) under atmospheric pressure and it will freeze skin tissue.
z Never allow refrigerant R- 134a gas to escape in quantity in an occupied space. R- 134a is
non- toxic, but it will displace the oxygen needed to support life.
z Never use a torch in an atmosphere containing R- 134a gas. R-134a is non-toxic at all
normal conditions, but when it is exposed to high temperatures, such as a torch flame, it
decomposes. During decomposition it releases irritation and toxic gases (as described in
the MSDS sheet from the manufacturer). Decomposition products are hydrofluoric acid,
carbon dioxide and water.
z Do not allow any portion of the charged air conditioning system to become too hot. The
pressure in an air conditioning system rises as the temperature rises and temperatures
of approximately 85°C (185°F) can be dangerous.
z Allow the engine to cool sufficiently prior to carrying out maintenance or serious burns
and injury can occur.
CAUTION: To avoid damaging the vehicle or A/C components, the following precautions
must be observed:
zThe A/C refrigerant of all vehicles must be identified and analyzed prior to refrigerant
charging. Failure to due so can contaminate the shop bulk refrigerant and other vehicles.
z Do not add R- 12 refrigerant to an A/C system that requires the use of R- 134a refrigerant.
These two types of refrigerant must never be mixed. Doing so can damage the A/C
system.
z Charge the A/C system with the engine running only at the low- pressure side to prevent
refrigerant slugging from damaging the A/C compressor.
z Use only R- 134a refrigerant. Due to environmental concerns, when the air conditioning
system is drained, the refrigerant must be collected using refrigerant recovery/recycling
equipment. Federal law REQUIRES that R- 134a be recovered into appropriate recovery
equipment and the process be conducted by qualified technicians who have been
certified by an approved organization, such as MACS, ASI etc. Use of a recovery machine
dedicated to R- 134a is necessary to reduce the possibility of oil and refrigerant
incompatibility concerns. Refer to the instructions provided by the equipment manufacturer when removing refrigerant from or charging the air conditioning system. SECTION 412-
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If two substances of different temperature are placed near each other, the heat in the warmer
substance will transfer to the colder substance.
Latent Heat of Vaporization
When a liquid boils (converts to a gas), it absorbs heat without raising the temperature of the resulting
gas. When the gas condenses (reverts back to a liquid), it gives off heat without lowering the
temperature of the resulting liquid.
Relative Humidity
The amount of moisture (water vapor content) that the air can hold is directly related to the air
temperature. The more heat there is in the air, the more moisture the air can hold. The lower the
moisture content in the air, the more comfortable you feel. Removing moisture from the air lowers its
relative humidity and improves personal comfort.
Effects of Pressure on Boiling or Condensation
As the pressure is increased on a liquid, the temperature at which the liquid boils (converts to a gas)
also increases. Conversely, when the pressure on a liquid is reduced, its boiling point is also reduced.
When in the gas state, an increase in pressure causes an increase in temperature, while a decrease in
pressure will decrease the temperature of the gas.
Compressor Anti-
Slugging Strategy
Liquid refrigerant may accumulate in the A/C compressor under certain conditions. To alleviate
damage to the A/C compressor, compressor anti- slugging strategy (CASS) is utilized.
CASS is initiated only under specific conditions:
zthe ignition is off for more than 8 hours
z the ambient temperature is above -4º C (25ºF)
z battery voltage is above 8.5 volts during engine cranking
When these conditions are present, the powertrain control module (PCM) will activate the A/C control
relay prior to cranking of the engine. The A/C control relay engages the A/C compressor for
approximately 4- 15 A/C compressor revolutions or a maximum of 2 seconds (depending upon vehicle
application), allowing the liquid refrigerant to be pushed from the A/C compressor. CASS is initiated by
the PCM regardless of the function selector switch position or the EATC system settings.
The Refrigerant Cycle
During stabilized conditions (air conditioning system shut down), the refrigerant is in a vaporized state
and pressures are equal throughout the system. When the A/C compressor (19703) is in operation, it
increases pressure on the refrigerant vapor, raising its temperature. The high- pressure and high-
temperature vapor is then released into the top of the A/C condenser core (19712).
The A/C condenser core, being close to ambient temperature, causes the refrigerant vapor to
condense into a liquid when heat is removed from the refrigerant by ambient air passing over the fins
and tubing. The now liquid refrigerant, still at high pressure, exits from the bottom of the A/C
condenser core and enters the inlet side of the A/C evaporator core orifice (19D990).
The A/C evaporator core orifice is the restriction in the refrigerant system that creates the high
pressure buildup upstream of the A/C evaporator core (19860) and separates the high and low
pressure sides of the A/C system. As the liquid refrigerant leaves this restriction, its pressure and
boiling point are reduced.
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