Carrier 38APS025 - A175 - Loss of Communication with AUX Board; T176 - 4 to 20 Ma Reset Input Failure; T177 - 4 to 20 Ma Demand Limit Input Failure; T303 - Coil - Scheduled Maintenance Due

175
A175 — Loss of Communication with AUX board
Criteria for Trip: A communication problem with the AUX
Board has been detected by the Main Base Board. The AUX
Board is required for digital compressor operation and low
ambient head pressure control (Motormaster
®
) operation.
Action to be taken: Functions associated with the AUX Board,
digital compressor and Motormaster controller operation are
stopped.
Reset Method: Automatic once the condition is resolved.
Possible Causes: If this condition is encountered, check the
following items:
• Check the configurations. If Compressor A1 Digital
Configuration
o
UNIT
o
A1.TY=YES and no AUX
Board is installed, this alarm will be generated. Simi-
larly, if Motormaster Select Configuration
o
M.MST
o
MMR.S=YES and no AUX Board is installed, this alarm
will be generated.
• Check the address of the AUX Board.
• Check the LEN wiring to the AUX Board.
• Check the power supply to the AUX Board.
T176 — 4 to 20 mA Reset Input Failure
Criteria for Trip: This alert indicates a problem has been
detected with reset 4 to 20 mA input. The input value is either
less than 2 mA or greater than 22 mA.
Action to be taken: The cooling reset function will be disabled
when this occurs.
Reset Method: Manual
Possible Causes: If this condition is encountered, check the
following items:
• Confirm the input signal the control is reading. Check
the value of 4-20 Reset Signal (Inputs Mode
o
4-20
o
RSET). Compare this to expected signal strength.
• Confirm signal polarity, LVT-8 (–) and LVT-9 (+)
• Confirm Energy Management Module configuration,
EMM Module Installed, Configuration
o
OPT1
o
EMM=YES.
T177 — 4 to 20 mA Demand Limit Input Failure
Criteria for Trip: This alert indicates that a problem has been
detected with demand limit 4 to 20 mA input. The input value
is either less than 2 mA or greater than 22 mA.
Action to be taken: The cooling demand limit function will be
disabled when this occurs.
Reset Method: Manual.
Possible Causes: If this condition is encountered, check the
following items:
• Confirm the input signal the control is reading. Check
the value of 4-20 Demand Signal (Inputs Mode
o
4-20
o
DMND). Compare this to expected signal strength.
• Confirm signal polarity, LVT-8 (–) and LVT-7 (+)
• Confirm Energy Management Module configuration,
EMM Module Installed, Configuration
o
OPT1
o
EMM=YES.
A200 — Indoor Fan Status Failure - Fan Not Running
Criteria for Trip: This alarm is generated when the following
conditions are true:
1. 38AP unit is Enabled (Inputs
o
GEN.I
o
STST=STRT).
2. Airflow switch is open (Inputs
o
GEN.I
o
ID.F.A=
OFF).
Action To Be Taken: Unit is not allowed to start, or is shut
down.
Reset Method: Automatic once the condition is resolved.
Possible Causes: If this condition is encountered, check the
following items:
• Confirm that airflow is present in the air handler if an air-
flow switch is used.
• Check airflow switch circuit wiring.
• If no airflow switch is used, confirm the jumper is in
place between LVT-16 and LVT-18.
T201 — Circuit A Indoor Fan Status Failure - Fan Not
Running
T202 — Circuit B Indoor Fan Status Failure - Fan Not
Running
Criteria for Trip: This alarm is generated when the following
conditions are true:
1. 38AP unit is Enabled (Inputs
o
GEN.I
o
STST=STRT).
2. Control Type is Dual Thermostat (Configuration
o
OPT2
o
C.TYP=8).
3. Airflow switch 1 is open (Inputs
o
GEN.I
o
ID.F.A=
OFF) (T201) or airflow switch 2 is open (Inputs
o
GEN.I
o
ID.F.B=OFF) (T202).
Action To Be Taken: For T201, circuit A is not allowed to start,
or is shut down. For T202, circuit B is not allowed to start, or
is shut down.
Reset Method: Automatic once the condition is resolved.
Possible Causes: If this condition is encountered, check the
following items:
• Confirm that airflow is present in the air handler if an air-
flow switch is used.
• Check airflow switch circuit wiring.
• If no airflow switch 1 is used, confirm the jumper is in
place between LVT-16 and LVT-18 for T201.
• If no airflow switch 2 is used, confirm the jumper is in
place between LVT-17 and LVT-18 for T202.
T303 — Coil - Scheduled Maintenance Due
Criteria for Trip: This alarm is generated when the Coil Ser-
vice Countdown (Run Status
o
PM
o
COIL
o
C.L.DN) has
expired.
Action To Be Taken: None, service alert only.
Reset Method: Manual. Perform coil maintenance. Before the
alert can be cleared, Coil Cleaning Maint Done (Run Status
o
PM
o
COIL
o
C.L.MN) must be toggled from NO to YES.
Reset the alert.
Possible Causes: If this condition is encountered, check Coil
Service Countdown.
T500 — Current Sensor Board A1 Failure
T501 — Current Sensor Board A2 Failure
T502 — Current Sensor Board A3 Failure
T503 — Current Sensor Board B1 Failure
T504 — Current Sensor Board B2 Failure
T505 — Current Sensor Board B3 Failure
Criteria for Trip: This alarm is generated when the Current
Sensing Board (CSB) output read by the Main Base Board
(MBB) or Compressor Expansion Module (CXB) is at a con-
stant high value.
Action To Be Taken: Affected compressor is shut down.
Reset Method: Automatic, when signal returns to normal.
Possible Causes: If this condition is encountered, check the
following items:
• Check the CSB to be sure that it is wired properly.
• On 208 volt systems, be sure that the control transformer
is wired for 208 volts. It has been noted with some sys-
tems that operate on 208 volts, when the wire is located
on the 230 volt tap, nuisance T500-T505 alarms have
been generated.
• Consider replacing the CSB.
o
515