Carrier 48FC Series User Manual

37
Economizer Troubleshooting
Use the SystemVut 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--20mA output signal must be converted to 2 --10V.
Feedback from the actuator is a 2 to 10 volt feedback. If the
feedback does not reach 2 volts when commanded to 0% a negative
trim (ECO FEEDBACK TRIM in the Service Calibration menu) can
be put on the fe edbac k to stop Econom i zer al arms occurring at 0%. If
this done the ma x dampe r position (ECON MAX POS in the
Economizer Settings menu) must be set less than 100% to prevent
Economizer alarms at 100% since the trimmed value will not reach
100% at 10 Volts. Both signals can be measured with a meter on
the signal and feedback wires J7 pins 4 and 3 respectively and
referenced to ground J7 pin 8 while the values can be displayed on
the local display.
The Economizer alerts can be summarized as a failure to modulate
the damper blades. This can be due to the actuator not being
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 temperature
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.
Table 16 – 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 heati ng or cooling.
Tripped circuit breaker.
No power to the unit.
Unit is off via CCN comman d.
Actuat or is unplugged at mot or or at
economizer board.
Check wiring connection s.
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
R
IAQ --- I n d o o r A i r Q u a l i t y

Carrier 48FC Series Specifications

General

Brand	Carrier
Model	48FC Series
Category	Air Conditioner
Language	English