Graco Reactor H-25 Series Repair And Parts Manual page 25

Pumps Do Not Reverse Direction
1. For the proportioning pumps to reverse direction,
the activator plate (219) must contact the rocker arm
to activate the reversing switch (210). Check for a
bent or loose activator plate, rocker arm, or
reversing switch. See F
parts drawing on page 57.
2. Check the function of the directional valve. Direction
indication lights should switch on and off based on
the reversing switch (210) position. LEDs D19 and
D20 (near J5 reversing switch connector on motor
board) should alternately illuminate based on the
reversing switch position.
There are two possible problems with the directional
valve:
a. If D19 and D20 do not alternately illuminate, the
possible causes include:
• faulty reversing switch wiring,
• faulty reversing switch, or
• faulty motor board.
To resolve this problem:
• verify the continuity of each reversing
switch wire. Replace faulty wires.
• verify reversing switch. Unplug the J5
reversing switch connector. Verify that
continuity alternates between NC2 to com
and N03 to com by toggling the reversing
switch (see Electrical Diagrams manual). If
continuity does not alternate, replace the
reversing switch and reconnect the J5
reversing switch connector.
• if the reversing switch and wiring are not the
cause, and D19 and D20 will not alternately
illuminate, replace the motor board.
312063Z
. 1 on page 24, and the
IG
b. If D19 and D20 do illuminate but the direction
indication lights do not, the possible causes
include:
• faulty motor board,
• faulty directional valve wiring, or
• faulty directional valve.
To resolve this problem:
• verify the motor board output voltages at
the J18 directional valve connector. When
the reversing switch is toggled one
direction, there should be 230V output
between pins 1 and 2 (A+ and A-). When it
is toggled the other direction, there should
be 230V output between pins 3 and 4 (B+
and B-). If output voltages are not present,
replace the motor board.
• verify continuity of each directional valve
wire and verify wiring connections (see
Electrical Diagrams manual).
• if motor board and wiring are not the cause,
replace the directional valve.
NOTE: For diagnostic purposes, it is possible to
manually override the directional valve by using a small
screwdriver to depress the button in the center of either
directional valve end cap. Depressing the button in the
right end cap should cause the pump to travel to the
right. Depressing the left button should cause the pump
to travel to the left.
3. If you have determined that the cause is none of the
above, check for a loose piston packing retaining
bolt. This causes the piston to contact the inner face
of the pump inlet flange before the activator plate
contacts the rocker arm. Shut down the unit and
disassemble the appropriate pump for repair.
Troubleshooting
25