Ford 2003 Mustang Workshop Manual page 3177

An A/C compressor pressure relief valve is incorporated into the compressor A/C manifold and tube to:
relieve unusually high refrigerant system discharge pressure buildups. For specifications
regarding operating pressure(s), refer to
prevent damage to the A/C compressor and other system components.
avoid total refrigerant loss by closing after the excessive pressure has been relieved.
A/C Condenser Core
The A/C condenser core has the following characteristics:
It is an aluminum fin and tube design heat exchanger located in front of the vehicle radiator
(8005).
It cools compressed refrigerant gas by allowing air to pass over fins and tubes to extract heat
and by condensing gas to liquid refrigerant as it is cooled.
Refrigerant Lines
The condenser to evaporator tube (19835) contains the high pressure liquid refrigerant upstream of the
evaporator core orifice.
The A/C manifold and tube (19D734) is attached to the A/C compressor, is sealed with O-ring seals,
and has the following features:
The upstream side contains low pressure refrigerant gas.
The downstream side contains high pressure refrigerant gas and a fitting used to mount a
serviceable high pressure A/C charge port valve.
The downstream side also contains a fitting used to mount the refrigerant containment switch
(3.8L) or dual-function pressure switch (4.6L). A long-travel Schrader-type valve stem core is
installed in the fitting so that the switch can be removed without discharging the A/C system.
Section 412-00 .