Ford 2003 Mustang Workshop Manual page 3067

Turn the function selector switch to each of the following
positions and note the resistance reading:
MAX A/C
A/C
VENT
FLOOR
MIX
DEFROST
Are any of the readings less than 10,000 ohms?
C11 CHECK CIRCUIT C198 (DG/OG) FOR A SHORT TO
GROUND
Connect: A/C Cycling Switch C130.
Disconnect: A/C Pressure Cut-off Switch C1078.
NOTE: The A/C pressure cut-off switch C1078 for the
3.8L engine is shown, C1078 for the 4.6L engines is
similar. The pin locations and the circuits are identical.
Measure the resistance between the A/C pressure cut-
off switch C1078-3, circuit 198 (DG/OG), harness side
and ground.
Is the resistance reading less than 10,000 ohms?
C12 CHECK THE A/C CYCLING SWITCH FOR A SHORT
TO GROUND
Disconnect: A/C Cycling Switch C130.
NOTE: The A/C pressure cut-off switch C1078 for the
3.8L engine is shown, C1078 for the 4.6L engines is
similar. The pin locations and the circuits are identical.
Measure the resistance between the A/C pressure cut-
off switch C1078-2, circuit 420 (DB/YE), harness side
and ground.
Yes
GO to C14 .
No
GO to C12 .
Yes
REPAIR circuit C420 (DB/YE)
for a short to ground. TEST for
normal operation.
No
INSTALL a new A/C cycling
switch. REFER to Section 412-
03 . TEST system for normal
operation.