Chapter 6: Alarms and System Failure Codes
Alarms
6-6 Service Manual
6.1.12 Fan Always in High Speed Alarm
6.1.13 Fan Failure Alarm
Cause or Circumstances Failure Action
Software cannot read
temperature of the heat sink
sensor in incubator heat sink.
Defective heat sink sensor or
harness
Check the heat sink temperature
sensor resistance in service Mode.
You can also check heat sink sensor
resistance by disconnecting the
harness from J3 at the control
board. Measure between pins 1 and
2.
If defective, remove the chassis
cover and disconnect the harness
from heat sink sensor. Measure
sensor resistance at pins 1-2 on the
sensor harness to determine if
sensor or harness is defective.
Defective control board If the heat sink sensor and harness
measure OK, then replace the
control board.
Cause or Circumstances Failure Action
Fan rotation is not being
detected.
Optical fan sensor not
detecting the fan
Note: System failure 25 and FAN
FAILURE are both triggered
by the optical fan sensor
not detecting the fan. If this
occurs at power-up, a
system failure 25 will
activate. If it occurs after
the power tests are
completed, the FAN
FAILURE alarm will activate.
Fan is not turning. Fan or fan hub not seated
properly
Verify the fan hub is properly
seated all the way down on the fan
shaft. (It may be necessary to wet
the part to get it to slide all the way
down on to the shaft.) Verify the fan
is seated in the groove at the top of
the hub.
Defective fan motor Replace the fan motor.
Defective relay board Replace the relay board.