43
Economizer Troubleshooting
Use the SystemVu™ Display to view the economizer status.
Check the current alerts and faults and the alarm history for
economizer specific alerts or any relevant faults or alerts and
correct those issues. Use test mode to troubleshoot by ramping
the economizer up and down with and without the indoor fan
and power exhaust fan on. Inspect the mechanical economizer
for actuator, gear, or blade damage. Ensure the actuator is
mounted with the correct spring return (close damper when no
power applied to unit). Ensure there is a 500 ohm resister
across the actuator as the 4 to 20mA output signal must be con-
verted to 2 to 10v.
The Economizer alerts can be summarized as a failure to mod-
ulate the damper blades. This can be due to the actuator not be-
ing properly connected to the damper, or because the actuator’s
feedback signal is indicating that damper is not performing as
commanded. The mechanical disconnect diagnostic will run
when conditions are appropriate to determine proper air tem-
perature changes. This uses the OAT, RAT, and SAT to tell if
the damper is mixing the outdoor air with the return air. The
other alerts inform where the damper is stuck relative to the
commanded position.
See Table 20 for economizer service analysis.
Table 20 — Economizer Service Analysis
PROBLEM POSSIBLE CAUSE REMEDY
Damper does not move
Indoor fan is off.
Check for proper thermostat connection.
Unit is not configured for continuous fan operation and the
thermostat is not calling for heating or cooling.
Unit is in Unoccupied mode and there is no call for heating
or cooling.
Tripped circuit breaker.
No power to the unit.
Unit is off via CCN command.
Actuator is unplugged at motor or at economizer
board.
Check wiring connections.
Unit is not configured for economizer. Configure unit for economizer per the instructions.
Outdoor-air temperature is above economizer
high temperature lockout.
Adjust the high temperature lockout setting if it is incorrect,
otherwise, economizer is operating correctly.
Outdoor-air temperature is below economizer low
temperature lockout.
Adjust the low temperature lockout setting if it is incorrect,
otherwise, economizer is operating correctly.
Communication loss to economizer board. Check wiring connections.
Damper is jammed. Identify the obstruction and safely remove.
Economizer operation is limited
to minimum position
Minimum position is set incorrectly. Adjust minimum position setting.
Outdoor-air temperature is above economizer
high temperature lockout.
Adjust the high temperature lockout setting if it is incorrect,
otherwise, economizer is operating correctly.
Outdoor-air temperature is below economizer low
temperature lockout.
Adjust the low temperature lockout setting if it is incorrect,
otherwise, economizer is operating correctly.
Enthalpy or differential dry bulb are preventing
free cooling.
Check enthalpy and return air compared to outside air
temperature.
Outdoor-air thermistor is faulty. Replace outdoor-air thermistor.
Low suction pressure problem with a compressor.
Economizer is operating correctly, identify compressor
problem.
Economizer position is less
than minimum position
IAQ is controlling minimum damper position.
Adjust the IAQ settings if incorrect, otherwise, the
economizer is operating correctly.
Unit is in Unoccupied mode.
Adjust unit occupied schedule if incorrect, otherwise,
economizer is operating correctly.
Economizer does not return
to minimum position
Unit is operating under free cooling. Economizer is operating correctly.
Damper does not close
on power loss
Damper is jammed or spring return is backwards. Identify the obstruction and safely remove.
Economizer is not at
configured minimum position
Unit is operating under free cooling or a force is
applied to the commanded position.
Economizer is operating correctly.
LEGEND
CCN — Carrier Comfort Network
®
IAQ — Indoor Air Quality
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