Economizer Troubleshooting; Title 24 Fdd Status Points - Carrier 48LC 04 Controls, Start-Up, Operation And Troubleshooting

Economizer Troubleshooting

Use the unit Scrolling Marquee display or a CCN device to view
the economizer status display and the economizer diagnostic
display (see Appendix A) for information on the economizer
operation. Check the current alarms and alarm history for any
economizer alarm codes and correct any causes. (See Table 6.)
Verify any unique control configurations per installed site
requirements or accessories. If alarms conditions are corrected and
cleared, operation of the economizer may be verified by using the
Service Test mode (see Service Test section and Table 4). The
following steps specify how to test the economizer using the
Scrolling Marquee display. See Table 9 for general economizer
service analysis.
1. Enter the Service Test main menu on the display.
2. Enter TEST and turn ON test mode. A password may be
needed in order to turn ON the Service Test. The default
password is 1111.
3. Return to the main level of Service Test.
4. Enter the INDP submenu and enter an initial value for
ECON. This will drive the economizer damper to the
specified position. Continue to adjust the ECON value to
make sure the economizer opens and closes.
5. Because of a mechanical problem with the economizer, the
actuator might acquire a new degree of rotation which is
less than M.ANG. If this occurs, a "T414 Economizer
Damper Actuator Out of Calibration" alert will be
generated. This alert can only occur if the economizer is
using digital communications
ECONE.CTL = 1 or 2). The economizer calibration
procedure (Service TestIND.PE.CAL) will reconfigure
the actuator to the new fully closed and fully open
positions. To implement the calibration procedure, change
E.CAL from OFF to ON. E.CAL will remain ON as long as
the calibration procedure is being implemented (as long as 5
minutes). During the calibration procedure the actuator will
close fully and then open fully. After the calibration is
complete, the degree of rotation should be greater than
M.ANG, causing the T414 alert to clear. If the T414 alert
does not clear, check the economizer damper for other
mechanical problems.
6. Return to Service TestTEST and turn OFF test mode.
This will cause the unit to return to normal operation.

Title 24 FDD Status Points

The control shall utilize the following points to determine whether
a damper is mechanically disconnected:
ECONO - - "Economizer Installed" - - Flag indicating whether an
economizer is installed
RAT - - "Return Air Temperature"
SAT - - "Supply Air Temperature"
OA_TEMP - - "Outdoor Air Temperature"
OCCUPIED - - "Currently Occupied" - - Flag indicating whether
currently in occupied mode
IDF_MODE - - "Indoor Fan Mode" - - Current indoor (supply) fan
mode.
IDFSTATE – "Indoor Fan State"
FANSPEED - - "Commanded Fan Speed" - - Commanded fan speed
ECONOCMD - - "Econo Commanded Position" - - Economizer
position as commanded by the ComfortLink control
ECONOPOS - - "Econo Actual Position" - - Economizer position as
reported by the actuator
ECONCOOL - - "OK To Use Economizer?" - - Flag indicating whether
the economizer is able to help with cooling without taking into
account whether the supply fan is on.
OKTSTMDA - - "OK Test Mech. D/C Act" - - Flag indicating
whether the control will attempt to test for a mechanically
disconnected actuator.
T24PRSAT - - "Title 24 Previous SAT" - - SAT sample taken at
T24ECSMP
(Configuration
T24ECSMP - - "Title 24 Econ Samp Pos" - - Economizer position
when T24PRSAT taken
T24SATCT - - "Title 24 SAT Check Time" - - Time when next SAT
sample will be taken or test for mechanically disconnected actuator
will be performed.
ELAPSECS - - "Elapsed Seconds" - - Current ComfortLink control
elapsed seconds
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