Repair manual

MT1828
5 --- 5
CONVECTION SYSTEM
POSSIBLE CAUSE(S) SUGGESTED REMEDY
Symptom #1 --- Blower motor(s) not running
D Oven in OFF mode.
D Remote emergency stop switch on OFF.
D No power to oven.
D Motor circuit breaker tripped.
D Faulty start capacitor.
D Motor(s) burnt out.
D Motor contactor open.
D Thermal overload t ripped.
D Press ON/OFF key.
D Pull switch out to ON.
D V erify power to motor(s). If there is voltage pres-
ent, replace the motor. If voltage is not present,
check the motor contactor.
D Replacefuse.Determineampdraw.
D Replace capacitor.
D Check draw (3amps or greater) when the oven is
cold.
D Check that the computer is turned on and that a
cook time and temperature have been pro-
grammed. Check for voltage to the coil of the mo-
tor contactor. If voltage is present, replace the
contactor. If voltage is not present, check that the
blower relay is closed. If not, check for voltage at
the blower relay coil. If a 12 VDC voltage is pres-
ent at the coil the blower relay is bad. If there is
no voltage present at the coil the computer may
need to be replaced.
D Determine if the cooling blower (or fans) are oper-
ating. If not, verify voltage to the cooling blower.
If voltage is present, replace the cooling blower
motor. If voltage is not present, verify voltage
through the thermal sw itch. If no voltage is pres-
ent, replace the thermal switch.
Symptom #2 --- Blower motor(s) do not shut off
D Faulty motor contactor.
D Faulty blower motor relay.
D Faulty auxiliary contact.
D Faulty probe.
D Replace contactor.
D Replace relay.
D Replace auxiliary contactor.
D Use the chart in the Technical Appendix (page
NO TAG) to determine if probe is bad. Replace if
necessary.
Symptom #3 --- Hood system does not operate when oven is on
D Fan exhaust/supply problem.
D Defective interlock circuit.
D Contact HVAC service.
D Replace auxiliary contactor.