Service Procedure D24; Main Burner Operation Testing - andrews 24/39 Installation And Service Manual

10 Appendix
10.7 Service procedure D24-III
Condition:
Main burner will not light, Display
shows "Heating" under
temperature setpoint. Tank is cold.
Is pilot lit?
Yes
Does control board continue to
spark with pilot lit?
No
Insert meter probes into back of
"Control" plug on control board to
contact pins for measuring voltage.
Is there 22-27 volts AC across pin
terminals 5 & 8? (Refer to wiring
diagram)
Yes
Disconnect brown wire lead from
"MV" terminal of gas valve.
Is there 22-27 volts AC across
brown wire lead & ground?
No
Check wire harness for damage or
loose connections. Repair or
replace as needed.
98
No
See "pilot will not light"
Yes
See "pilot lights, no flame signal"
Be sure control display is showing
"Heating", pilot is lit and control
No
is not sparking. Recheck voltage
across control board
pin terminals 5 & 8 (MV & MV/PV)
Is voltage present?
Check incoming gas pressure to
gas valve and manifold pressure to
Yes
burners (See next page for
procedure or checking manifold
pressure). If inlet gas pressure is
O.K., replace gas valve.

10.7.1 Main burner operation testing

Danger
120 volt exposure. To avoid personal injury, use caution
while performing this procedure.
Caution
Be Careful When Making Voltage Measurements or
Jumping Terminals Not to Damage or Deform Connectors
or Connector Pins.
No
Yes
Replace control board.
Issue 2 14/07/16