Carrier SUPRA 850Mt Operation And Service Manual page 35

AL16: Compartment 3 Return Air Sensor Alarm
The Compartment 3 return air sensor alarm is dis-
played with the description 3RA SENSOR or AL16. This
alarm is generated if the return air sensor is open or
shorted. The fault light (FL) is turned on because there
is no controlling probe.
AL17: Display Alarm
When no communications exist between the main
board and the display board for eight seconds, the dis-
play alarm description is DISPLAY or AL17
AL18: Maintenance Hour Meter 1 Alarm
The Maintenance Hour Meter Alarm 1 is displayed
with the description SERVICE 1 or AL18. This alarm is
generated when the designated hour meter is greater
than maintenance hour meter 1.
AL19: Maintenance Hour Meter 2 Alarm
The Maintenance Hour Meter Alarm 2 is displayed
with the description SERVICE 2 or AL19. This alarm is
generated when the designated hour meter is greater
than maintenance hour meter 2.
AL20: Compartment 1 Out-of-Range Alarm
The out-of-range alarm is displayedwith the descrip-
tion 1RA OUT or AL20. This alarm is generated when
compartment 1 is out-of-range (refer to FN8 section
2.8.6). The fault light (FL) is turned on.
AL21: Compartment 2 Out-of-range Alarm
The out-of-range alarm is displayedwith the descrip-
tion 2RA OUT or AL21. This alarm is generated when
Compartment 2 is out-of-range (refer to FN8 section
2.8.6). The fault light (FL) is turned on.
AL22: Compartment 3 Out-of-range Alarm
The out-of-range alarm is displayedwith the descrip-
tion 3RA OUT or AL22. This alarm is generated when
Compartment 3 is out-of-range (refer to FN8 section
2.8.6). The fault light (FL) is turned on.
AL23: No Power for Standby Alarm
"NO POWER" will be displayed if truck unit is swit-
ched to standby and power plug is not plugged in.
AL26: Suction Pressure Alarm
The system check alarm will be displayed with the
description SYSTEM CK or AL26. The fault light (FL) is
turned on. If the unit is in cool mode and the supply air
temperature becomes 5
air temperature for continuous minutes then the alarm
will be activated. If the suction pressure becomes grea-
ter than 6.9 bars (100 PSI) in heat mode for 60 conti-
nuous seconds for both perishable and frozen setpoints
the alarm will be activated. If the suction pressure beco-
F ( 3 C) higher than the return
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mes less than --0.3 bars (--5 PSI) for 120 continuous
seconds while any compartment is in cool mode and
while the return air temperature for the cooling compart-
ment is > --17.8
is greater or equal to 4.4
vated.
2.8.9 Heat/Cool mode
Thesystem is configuredfor cooling mode forengine
or standby start (default mode). Once unit is considered
running it will maintain setpoint temperature by switch-
ing between heat and cool.
2.8.10 Defrost cycle
Defrost is an independent cycle (overriding cooling
and heating functions) to de-ice the evaporator as re-
quired. The controller displays "DF" duringdefrostmode
on theright hand temperature display. Theleft hand dis-
play will continue to display the setpoint.
There is 2 ways of initiating a defrost.
Method one to initiate defrost is by pressing the
Manual defrost key
Method two is that defrost may be initiated automati-
cally at preset intervals by defrost timer in themicropro-
cessor.
1. Automatic defrost initiation
A defrost will be initiated if the defrost time (entered
via the keypad) is elapsed.
The defrost timer is reset to zero whenever a defrost
cycle is initiated. Thecontroller holds in memory the last
entered defrost interval.
The defrost timer runs only when the defrost ther-
mostat is closed (DTS)
2. Defrost function
After initiation, defrost mode terminates when the
defrost termination thermostat (DTS) opens indicating
that the evaporator is de- -iced.e defrost cycle is com-
plete. The defrost timer runs only when the DTS is
closed. The timer does not accumulate time during de-
frost mode, during standby off cycles or auto-start off
cycles.
The compressor operates at maximum capacity
(engine forced in high speed) during defrost.
3. Fail safe defrost termination
Should the defrost cycle not complete within 45 min-
utes or if the external defrost signal does not clear at de-
frost termination, the defrost cycle is terminated. The
internal timer is reset for 1.5 hours and the external de-
frost signal is ignored for defrost initiation. The manual
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C (0 F) and the ambient temperature
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C(40 F) the alarm will beacti-
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