Heating Failure; Troubleshooting The 24Vac Circuit - Frymaster BIELA14-T Series Service Manual

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Heating Failure

Heating failure occurs when the heating contactor fails to stay engaged and locks out. When this happens, the module
sends 24 VAC through the interface board alarm circuit to the controller.
M4000 controllers display "HEATING FAILURE".
The three primary reasons for heating failure, listed in order of probability, are problems related to:
1. Electrical power supplies
2. Electronic circuits
3. Contactor issues
PROBLEMS RELATED TO THE ELECTRICAL POWER SUPPLIES
The main indicators of this are that the fryer does not operate and there are no indicator lights illuminated on the fryer
experiencing heating failure. Verify that the fryer is plugged in with connector twisted and locked and the circuit breaker
for the fryer electrical supply is not tripped.
PROBLEMS RELATED TO THE ELECTRONIC CIRCUITS
If electrical power is being supplied to the fryer, the next most likely cause of heating failure is a problem in the 24 VAC
circuit. Verify that the transformer is operating correctly. Refer to Section 1.7.4.
TROUBLESHOOTING THE 24 VAC CIRCUIT.
Some typical causes of heating failure in this category include a defective transformer, a defective relay, a defective
contactor, defective smart interface board (SIB) or defective elements.
1.7.1 Troubleshooting the 24 VAC Circuit
Prior to checking for problems associated with the 24 VAC circuit, ensure that the unit is connected to a power supply, and
the controller is on and is calling for heat (heat indicator appears and displays PRE-HEAT).
NOTE: All voltage measurements must be made within 4 seconds of the unit calling for heat. If unit has an error the
controller may lock out and controller must be turned off, then on to reset.
DO NOT CHECK WITH HARNESSES UNPLUGGED AS SHORTING THE PINS MAY OCCUR WHICH WILL DAMAGE THE
BOARD.
The following processes will assist you in troubleshooting the 24 VAC circuit and ruling it out as a probable cause:
24 VAC is not present on the interface board J1 pin 1.

1. If LED's 2, 4 and 6 are not continually lit, the probable causes are a loose or blown fuse, failed 24 VAC transformer,
or failed wiring between the transformer and interface board.
24 VAC is present on interface board J1 pin 1.

1. If 24 VAC is not present at the latch contactor, the probable causes are an open high-limit thermostat, a failed latch
relay or a failed wire between the interface board and the latch contactor or a failed interface board.
a. Check continuity of high-limit thermostat. If it is zero, problem is in wiring.
2. If 24 VAC is not present at the heat contactor, the probable causes are a failed heat relay, latch contactor a failed
latch contactor, or a failed wire between the interface board and the heat contactor, a failed optional tilt switch or
a failed interface board.
3. If LED 3 is not continually lit with the controller in the ON position, the probable cause is a defective latch relay.
4. If LED 1 is not continually lit with the controller in the ON position and calling for heat, the probable cause is a
defective heat relay.
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