62-11389
7
−
67
Alarm
NO.
Steps
Alarm/Cause
Corrective Action
123
CHECK SUPPLY AIR SENSOR
•
TRIGGER–ON: Supply Air Temperature Sensor (1SAT) is not within the range of -53 to +158
°
F
(-47 to +70
°
C.)
•
UNIT CONTROL: Engine and standby:
If Alarm 122 is not active and functional parameter Temperature Control is set for Supply Air and
the set point for is in the perishable range: alarm only and switch to return air control.
If Alarm 122 is active: set unit control as described in Alarm 122.
•
RESET CONDITION: Auto Reset when Supply Air Sensor is in range or, alarm may be manually
reset via keypad or by turning the unit off, then back on again.
NOTE: Follow the steps below until a problem is found. Once a repair or correction has been made, the active
alarm should clear itself (see reset condition above). Operate the unit through the appropriate modes to see if
any active alarm occurs. Continue with the steps below as necessary.
1
Check Sensor
a. Inspect sensor & connectors.
No damage to sensor.
No damage, moisture, or corrosion in connectors.
b. Check sensor resistance. (See
Note 3, page 7
−
2.)
10,000 Ohms @ 77
°
F (25
°
C.) See Table 8
−
5 for
complete table of temperatures and resistance
values.
2
Check Sensor Wiring
a. Inspect harness & control box
connector pins & terminals. (1MP
& DP16, see wiring schematic
Section 10.)
No physical damage to harness.
No damage, moisture, or corrosion in connectors.
b. Power up the microprocessor (see
Note 2, page 7
−
2). Disconnect
sensor from harness. Check for
2.5 VDC at harness plug between
pins.
Voltage should be 2.5 VDC volts at harness plug be-
tween pins. This verifies microprocessor output and
wiring connections to the sensor.
