Ford 2003 Mustang Workshop Manual page 3055

Symptom Chart
Condition
Incorrect/erratic direction
of airflow from outlet(s)
Insufficient, erratic, or no
heat
The A/C does not
operate/does not operate
correctly
The A/C is always on
Insufficient A/C cooling
No operation in all the
temperature settings
The blower motor does
not operate
The blower motor
operates continuously in
Possible Sources
No vacuum to A/C heater
function switch selector.
A/C heater function selector
switch leaks vacuum.
Kinked/pinched vacuum hose.
Leaking vacuum control
motor.
Leaking A/C vacuum check
valve.
Leaking A/C vacuum reservoir
tank and bracket.
Vacuum actuator arm not
connected to door crank.
Low engine coolant level.
Thermostat stuck open.
Disengaged/damaged
temperature cable.
CASS strategy failure.
Open fuses.
A/C clutch relay.
Shorted blend door actuator.
Powertrain control module.
Circuitry short/open.
A/C cycling switch damaged.
A/C system discharged/low
charge.
Function selector switch
damaged.
A/C pressure cut-off switch
damaged.
A/C compressor clutch
damaged.
Circuitry short/open.
A/C cycling switch.
A/C heater function selector
switch.
Constant control relay
module.
Incorrect A/C clutch air gap.
Restricted A/C evaporator
core orifice.
Low refrigerant level.
Damaged blend door actuator
cable.
Damaged air temperature
control door.
Open fuse.
Circuitry open/shorted.
Damaged heater blower
motor switch (18578).
Damaged heater blower
motor switch resistor (18591).
Damaged blower motor relay.
Damaged blower motor.
Circuitry short/open.
Damaged heater blower
Action
Go To
Pinpoint
Test A .
Go To
Pinpoint
Test B .
Go To
Pinpoint
Test C .
Go To
Pinpoint
Test D .
Go To
Pinpoint
Test E .
Go To
Pinpoint
Test F .
Go To
Pinpoint
Test G .
Go To
Pinpoint