andrews Fastflo WHC56 Service Manual page 34

5. Gas proportioning valve error.
6. Bypass flow control valve error.
7. Main flow control valve error.
Check the gas proportioning valve error.
(1) Check to see if the flame size changes when
pressing the minimum and maximum manifold
pressure set button, then measure the voltage
between Red 2 and Blue 4 using connector 38
on the circuit board.
DC 0.3 - 15V
Normal
Continue to "6. Bypass flow...".
Yes
Change the gas proportioning valve.
No Replace the circuit board.
Check the bypass flow control valve.
(1) Measure the following voltages using
connector 38 on the circuit board: between
Blue 25 - Black 18, Blue 25 - Orange 15,
Blue 25 - Green 16, and Blue 25 - Violet 17.
DC 1 - 16V
Normal
Yes Replace the bypass flow control valve.
No Replace the circuit board.
Check the main flow control valve error.
(1) Measure the following voltages using
connector 38 on the circuit board : between
Blue 25 - Black 30, Blue 25 - Orange 26,
Blue 25 - Green 27, Blue 25 - Violet 28.
DC 1 - 16V
Normal
Yes Replace the main flow control valve.
No Replace the circuit board.
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