7–111 62-12259
07006 Suction Pressure Sensor
• ACTIVATION: Suction pressure sensor is out of range. If Economizer pressure < or = (Suction pressure -
10) for 10 seconds and suction pressure is > than 40 psig and < than 60 psig with the compressor running.
• UNIT CONTROL: Engine and Electric: Alarm only. Economizer forced to STANDARD mode when alarm
is active.
• RESET CONDITION: Auto reset when Suction Pressure Sensor is in range or, alarm may be manually
reset using the display mounted keys 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 (refer to reset condition above). Operate the unit through the appro-
priate modes to see if any active alarm occurs. Continue with the steps below as necessary.
Corrective Actions:
1. Check System Pressures
a. Check Unit Data. Refer to Section 3.15. Compare the pressure readings for the ECOP, the CSP and
the CDP. The ECOP should read between the CSP and the CDP. Refer to Section 8.8.11 for
instruction on comparison. If pressures are in normal range, proceed to next step.
b. Place the Unit in Service mode. Refer to Section 5.2.5. After the unit has equalized, compare the
pressure readings for the ECOP, the CSP and the CDP. The ECOP the CSP and the CDP should all
read within 5 PSI, if not it indicates a failed sensor. Refer to Section 8.8.11 for instruction on
comparison.
2. Check Pressure Sensor - Inspect sensor and connectors (1-3MSM-9, 21, and 32). Verify there is no
damage to sensor, and no damage, moisture, or corrosion in connectors.
07008 Check Redundant Return Air Sensor (RAT2)
• ACTIVATION: A Redundant Return Air Temperature Sensor (RAT2) is installed, configured, and is not
within the range of -53 to +158°F (-47 to +70° C).
• UNIT CONTROL: Engine and Electric Operation: If RAT2 is selected as the active probe, switch active
probe to RAT probe.
• RESET CONDITION: Auto reset when sensor is in range or, alarm may be manually reset using the
display mounted keys 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 (refer to reset condition above). Operate the unit through the appro-
priate modes to see if any active alarm occurs. Continue with the steps below as necessary.
1. Check Sensor
a. Inspect sensor and connectors. Verify there is no damage to sensor, and no damage, moisture, or
corrosion in connectors.
b. Check sensor resistance. (Refer to Note 3 in Notes Section) 10,000 Ohms @ 77°F (25°C). Refer to
Table 8–5 for chart of resistances for different sensors.
2. Check Sensor Wiring
a. Inspect connector pins and terminals at sensor connector
(1-3MSM-18 and 29).
(See wiring
schematic
Section 10.2
) Verify there is no physical damage to harness, and no damage, moisture,
or corrosion in connectors.
b. Place the system in PC mode. Refer to Note 2 in Notes Section Disconnect sensor from harness.
Check for 3.0 ± 0.1 VDC at harness plug between pins. Voltage should be 3.0 ± 0.1 VDC volts at
harness plug between pins. This verifies microprocessor.
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