Diagnostic flow charts:
F-755-028
Rev. E
9/16/16
HA
Is the box temp cycling at the
set point plus the differential?
See
Checking the controller
Set point
No
YES
Is the “AU” Set point
programmed for factory default?
See
Resetting the program to
factory default settings
Replace the
Controller
YES
No
See
Warm Box
Diagnostic Flow Chart
LA
Does the probe resistance
match the associated
temperature of
Table 1
?
Yes
No
Replace the
Probe
YES
Is the “AL” Set point
programmed for factory default?
See
Resetting the program to
factory default settings
YES
Does the probe resistance
match the associated
temperature of
Table 1
No
No
No
Yes
Replace the
Controller
Replace the
Probe
Is the controller relay
stuck closed?
See
Checking the
Controller compressor
relay
Is the refrigeration
system running?
Is the box temp cycling at the
set point plus the differential?
See
Checking the controller
Set point
Replace the
Controller
No
No
Reprogram
See
Resetting the program to
factory default settings
Yes
Does the probe resistance
match the associated
temperature of
Table 1
?
Yes
Replace the
Probe
No
Yes
Reprogram
See
Resetting the program to
factory default settings
Reprogram
See
Resetting the program to
factory default settings
Warm
Box
Are the
compressor
and all
fans running?
No
Is the controller calling for
cooling? A snowflake will
appear on the display
Is the controller set
at the desired set point?
See
Checking the
Controller set point
YES
No
YES
Reprogram
See
Changing the
controller set point
YES
No
Is the probe
touching the
evaporator?
No
Yes
Is there continuity
across the controller
compressor relay?
See
Checking the
controller compressor
relay
Reposition the
probe
Does the probe resistance
match the associated
temperature of
Table 1
?
Yes
No
Replace the
Probe
Replace the
Controller
No
Yes
Check for bad
compressor,
fans, or wiring
Check for
refrigeration issues
or air infiltration
