Repair manual

MT1828
5 --- 3
HEATING SYSTEM
POSSIBLE CAUSE(S) SUGGESTED REMEDY
S y m p t o m # 1 --- B u r n e r w i l l n o t f i r e
D Oven in OFF mode.
D Emergency stop switch on OFF.
D Control circuit break er tripped.
D Combustion motor not running.
D Main Temperature Controller not set above ambi-
ent temperature.
D Manual gas valve closed.
D Intermittent Ignition Device (IID) system locked
out.
D Air pressure switch may be open.
D Blower motor(s) not running.
D High Limit control tripped.
D Thermal s witch in control compartment tripped.
D Excessive intake air temperature.
D Heat relay defective.
MT1828G CE approved units
D Prepurge timers defective.
D Triple pole double pole relay defective.
D Gas valve defective.
MT1828E only
D Contactor coil powered but will not close.
D Elements open.
D Turn to ON position.
D Pull switch out to ON.
D Reset breaker.
D Check transformer for primary and secondary
voltage.
D Check main control and burner valve relays to
see if closed.
D Check relay in combustion burner box. If bad re-
place relay.
D Set to desired temperature.
D Open valve.
D Reference Technical Appendix (page NO TAG
through NO TAG).
D Check convection blower (or 4 convection fans)
forproperoperation.
D V erify voltage to motor. If voltage is present, re-
placethemotororstartcapacitor.
D Verify that 625_F (330_C) high limit is pro-
grammed into the controller. If so reset the high
limit. Set the computer to 500_F (260_C). U se a
pyrometer to verify the oven temperature. If the
oven climbs significantly above the setpoint, use
the chart in the Technical Appendix (page
NO TAG) to check the probe. If the probe is al-
right the computer may need replacement.
D Check hood system.
D Check hood system.
D Replace heat relay.
D Replace t imers.
D Replace relay.
D Replace gas valve.
D Bad contactor, replace.
D Replace elements.