Yes
GO to
C6
.
No
GO to
C9
.
C6
CHECK THE A/C CYCLING SWITCH
NOTE:
The outside temperature must be over 10° C (50° F).
Connect a fused jumper lead between the A/C cycling switch C139 pin 1, circuit 441 (RD/YE) and pin 4, circuit
347 (BK/YE).
Does the A/C compressor clutch engage?
Yes
GO to
C7
.
No
GO to
C8
.
C7
CHECK THE A/C SYSTEM PRESSURE
Connect the manifold gauge set. Refer to
Manifold Gauge Set Connection
in this section.
Is the pressure reading between 345 kPa (50 psi) and 1724 kPa (250 psi)?
Yes
INSTALL a new A/C cycling switch. TEST the system for normal operation.
No
CHECK for refrigerant leaks. REFER to
Leak Detection—Using the Refrigerant Leak Detector
in this section.
C8
CHECK CIRCUIT 347 (BK/YE)
Remove the fused jumper lead from the A/C cycling switch C139.
A/C Cycling Switch C139
PCM C174
Connect the EEC-V 104-Pin Breakout Box to the PCM C174. Do not connect the breakout box to the PCM.
Measure the voltage between the breakout box pin 41 and ground.
Page 13 of 30
1999 F-150/250 Workshop Manual
8/16/2010
http://www.fordtechservice.dealerconnection.com/pubs/con...
