Pinpoint Test G: No Operation In High Blower Setting - Ford F-150 1999 Workshop Manual

1999 F-150/250 Workshop Manual
F5 CHECK THE BLOWER MOTOR SWITCH
F6 CHECK THE BLOWER MOTOR SWITCH RESISTANCE
Blower Motor Switch

PINPOINT TEST G: NO OPERATION IN HIGH BLOWER SETTING

CONDITIONS
G1 CHECK THE A/C BLOWER MOTOR OPERATION
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Is the resistance less than 5 ohms?
Yes
REPLACE the A/C blower motor resistor. RETEST the system for normal operation.
No
REPAIR Circuit 261 (O/BK). TEST the system for normal operation.
Turn the function selector switch to the FLOOR position and slowly rotate the blower motor switch from the LO
position to the HI position and back several times.
Does the A/C blower motor operate in all switch positions without interruption?
Yes
CHECK the system operations in all function selector switch positions and A/C blower motor speeds. If OK,
ADVISE the customer on correct operation of the system.
No
GO to F6.
Measure the resistance between the blower motor switch terminals in each switch position.
Switch Position Continuity Between Terminals
LO None
Low medium 2 and 3
High medium 2, 3 and 4
HI 1, 2 and 4
Is the resistance between the specified terminals less than 5 ohms?
Yes
CHECK for opens and shorts; REPAIR as required Circuits 752 (Y/R) or 754 (LG/W). RETEST the system for
normal operation.
No
REPLACE the blower motor switch. TEST the system for normal operation.
DETAILS/RESULTS/ACTIONS
Turn the function selector switch to the FLOOR position and the blower motor switch to the position next to the HI
position.
Does the A/C blower motor operate?
Yes
GO to G2.
No
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8/16/2010