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W:\ELECTRICAL\MANUAL\BENCH\GENERAL INSTRUCTIONS\BENCHOVEN INS.8-18
8 TROUBLE SHOOTING
8-1 NO HEAT
8-1.1 Excess temperature limit interlock actuation
The excess temperature limit interlock may be tripped by either an excessively
high oven temperature or a sensing element failure. Before placing the
equipment back into operation, it should be determined what caused the
excess temperature limit interlock to actuate and the condition be corrected.
Thermocouple actuated excess temperature limit interlocks are located in the
face of the control panel and have a reset button on the face of the interlock.
Fluid filled excess temperature limit interlocks are located at the rear of the
control panel and have a red reset button protruding from the control panel.
See the excess temperature limit interlock manufacturer's literature for the
proper operation and adjustment of the control used. In either type of interlock,
if the interlock fails to reset at room temperature, the sensing element has
failed. For thermocouple actuated excess temperature limit interlocks, the
thermocouples can be replaced. For fluid filled excess temperature limit
interlocks, the entire interlock must be replaced.
8-1.2 On/Off switch
Check for defective switch.
8-1.3 A fuse burned out or circuit breaker tripped
Make sure there is power at the oven.
8-1.4 Burned out heating element
Check there is power to each heating element and that elements are not open.
8.2 REDUCED OR INCORRECT OVEN TEMPERATURE
8-2.1 Excessive exhaust
The amount of heated air removed from the oven may be excessive and result
in a reduced operating temperature. In this case, the oven heat will be running
continuously. This can be corrected by reducing the exhaust until the
maximum operating temperature is achieved.
8-2.2 Door Leakage
Damaged door gaskets (Model NT and NTR only) combined with excessive
exhaust could result in cold air being drawn in around the doorway. Replace or
repair gaskets and reduce exhaust.
8-2.3 Fan Failure
Units with recirculating fans may have had a motor failure or the fan come
loose on the motor shaft. This results in reduced air flow and inefficient heat
transfer from the heating elements to the work space.
8-2.4 Defective or Improperly Calibrated Temperature Controller
See the temperature controller manufacturer's instructions for the proper
operation and adjustment for the specific controller used.
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