andrews 24/39, Installation Manual, Operation And Service Manual

Page: 81 / 96

APPENDICES
81
SERVICE PROCEDURE
D24-II
Pilot Operation Testing
CAUTION
Be Careful When Making Voltage
Measurements or Jumping Terminals
Not to Damage or Deform Connectors or
Connector Pins.
DANGER
120 volt exposure. To avoid personal injury,
use caution while performing this procedure.
Condition:
Pilot will not light or stay lit,
Error codes 62, or 63 shown on Water
Heater Display
Is there 22-27 volts AC output across
terminal pins 8 & 2 on “Control” plug
of Control Board? Carefully insert
meter probe in wire plug to check pin
terminals. Make sure control is in the
trial for ignition sequence (see
Sequence of Operation).
(see photo 13)
N
Y
Loosen pilot tubing connection at
the gas valve and soap test.
Is there pilot gas flow out of the
gas valve? See pilot illustration
for pilot inspection. (Wires must
be connected to gas valve during
this test).
Tighten pilot tube connection at
the gas valve. Check incoming
gas pressure to water heater. if
okay, replace gas valve
Check for clogged or kinked pilot
tube, clogged pilot orifice. Clean
or replace as needed.
(see “Pilot Burner Inspection”)
Is there 22-27 volts AC input across
wire leads
“MV/PV” & “PV” (yellow & red wires)
at Gas Valve ?
(see photo 12)
Check wire harness for damage or
loose connections. Repair or replace
as needed.
Reset control by pressing the lower
right button under “reset” on the
display for 3 seconds. Does control
board start ignition sequence and
start sparking (sparking noise at pilot
or at board)
Replace control board
12
Check across “MV/PV” & “PV” Wire
leads to gas valve
Y
Y
Y
N
N
Replace control board.
Is there spark at the pilot?
Check for:
Loose or damaged ignition wire
Grounded pilot electrode
Damaged pilot.
Y
N
Checking for 24
volts output to
pilot valve
(yellow and red
wire pin
terminals) on
control board
“control” plug.
N
Turn on power to the water heater
and verify proper operation
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