Troubleshooting; Complete Unit Stoppage; Restart Procedure; Alarms And Alerts - Carrier 48LC 04 Controls, Start-Up, Operation And Troubleshooting

CCN Alarm Broadcast
Operators of CCN networks might not want to be notified of
"striking" alerts for refrigerant circuits until the circuit has been
shut down due to 3 strikes. Set the cooling configuration of Alert
Each Strike (ConfigurationCOOLALM.N
ALM_NOW on CCN) to YES to broadcast each circuit strike alert.
Set Alert Each Strike to NO to broadcast only circuit shut down.
Alert Each Strike configuration is ignored during Service Test and
all alerts are broadcast.
Alarm Relay Output
The alarm relay output is a normally open 24 vac output between
field connection terminal board terminals C and X. Selection of
which alerts and alarms will result in closing of the alarm relay
may be set in the
(ConfigurationALM.O). Setting a configuration to YES will
result in the alarm output relay, ALRM, status of ON and 24 vac
between C and X on the field connection terminal board when that
particular condition is in an alarm state. Setting a configuration to
NO will result in no action by the alarm output relay for that
particular condition.
NOTE: An accessory filter switch can be used along with the
alarm relay output function to indicate dirty filter service need.
See the Troubleshooting section for more information on viewing,
diagnosing, and clearing alerts and alarms.

TROUBLESHOOTING

The Scrolling Marquee display shows the actual operating
conditions of the unit while it is running. If there are alarms or
there have been alarms, they will be displayed in either the current
alarm list or the history alarm list. (See Table 6.) The Service Test
mode allows proper operation of the compressors, fans, and other
components to be checked while the unit is not operating. See
Service Test.

Complete Unit Stoppage

There are several conditions that can cause the unit not to provide
heating or cooling:
S If an alarm is active which causes the unit to shut down,
diagnose the problem using the information provided in Alarms
and Alerts section below.
S Cooling and heating loads are satisfied.
S Programmed occupancy schedule.
S General power failure.
S Tripped 24-volt transformer circuit breakers.
S Blown fuse or circuit breakers
S Unit is turned off through the CCN network.
S If supply-air temperature is less than the Minimum SAT Lower
Level (SAT.L) configuration value, unit cannot cool.
S If outdoor-air temperature is less than the Compressor Lockout
Temperature (CA.LO) configuration value, unit cannot cool.
S If outdoor-air temperature is greater than the Heating Lockout
Temperature (HT.LO) configuration value, unit cannot heat.

Restart Procedure

Before attempting to restart the machine, check the alarm list to
determine the cause of the shut down. If the shutdown alarm for a
particular control function has occurred, determine and correct the
cause before allowing the unit to run under its own control again.
When there is problem, the unit should be diagnosed in Service
Test mode. The alarms must be reset before the control function
can operate in either Normal mode or Service Test mode.

Alarms and Alerts

Viewing and Clearing Unit Alarms
Presence of active alarms will be indicated on the Scrolling
Marquee display by the Alarm Status light turning on and by the
number of active alarms being displayed in the automatic View of
Run Status. Presence of active alarms may also be signaled on the
on display,
Alarm Relay Configuration
Alarm Output terminals. Each alarm may also be broadcast on the
CCN network. Active alarms and past alarm history can be
reviewed and cleared via the local display or a CCN device. The
following menu locations are used for the local display:
AlarmsR.CURR (Reset All Current Alarms)
Change to YES to reset all active alarms. Turning unit power off
will also reset all current alarms.
AlarmsR.HIST (Reset Alarm History)
Change to YES to reset the alarm history. Turning unit power off
will not reset the alarm history.
AlarmsCURR (Currently Active Alarms)
Use the ENTER key, then scroll through any alarm numbers using
the up and down arrow keys. Alarms are displayed in numerical
order.
AlarmsHIST (Alarm History)
Use the ENTER key, then scroll through any alarm numbers using
the up and down arrow keys. Up to 20 alarms are displayed in
order of occurrence, with time and date.
The description for an alarm can be viewed on the Scrolling
Marquee display by pressing ESCAPE and ENTER keys
simultaneously while displaying the alarm code number. Be sure to
expand description for each code, because in some cases there are
different possible descriptions and causes for the same code
number.
Diagnostic Alarm Codes and Possible Causes
Alert Code T051 (without Current Sensor)
This alert can only be activated if set to Diagnose Compressor
Safety (Configuration COOL D.CMP = Yes). There are 4
different texts for this alert code. There are two different alerts
which have corresponding test mode alerts indicated with "Service
Test" in the expanded text. Pressing enter and esc on the marquee
or navigator to expand the T051 alert will show you one of the
below alerts. Make sure the expanded text is read correctly before
troubleshooting.
S Compressor Safety Trip
This alert occurs when the respective compressor has been running
for 25 sec and the Saturated Suction Pressure (Pressures SSP.A)
reflects a change in compressor operation. A change in compressor
operation is when the SSP changes more than the Maximum
Suction Change configuration
MX.SA) in a two second window while running the compressor
and persists for 40 seconds. This alert can also occur when the
compressor is diagnosed with a high pressure switch trip. A high
pressure trip is when the compressor suction rises and falls two
times within 2 minutes.
When this occurs, the control turns off the compressor and logs a
strike for the circuit. This alert resets automatically. The possible
causes are: high- -pressure switch (HPS) open, Condensate
overflow switch (COFS) open, compressor internal protection is
open, or a wiring error (a wiring error might not allow the
compressor to start). The HPS and optional COFS are wired in
series with compressor relay on the MBB. If one of these opens
during compressor operation, the compressor stops causing the
control to activate this alert.
S Compressor Detected After Turnoff
This alert occurs when the compressor is turned off but the
Saturated Suction Pressure (Pressures SSP.A) does not reflect a
shutdown. When shutting down the compressor suction pressure
must rise more than Maximum Suction Change configuration
(Configuration COOL MX.SA) within the first 10 seconds
and stay above it. When this occurs, the control turns off the
compressor relay, stays in cooling mode and keeps the indoor fan
on. Use the Scrolling Marquee to reset the alert. The possible
causes are a welded contactor, frozen compressor relay on MBB, or
adverse conditions.
27
(Configuration
COOL