Unit Troubleshooting - Carrier 39L Series Installation, Operation, And Start-Up Instructions

PROBLEM
PIC control is OFF
Faulty connections
PIC control has incorrect time
Supply fan HOA switch in OFF position
Safety controls are tripped
Unit does not run
PIC control left in Quick Test
(Display shows Mode 38)
Unit is configured for and is currently
in Demand Limit Mode (CV units only)
Unit is in Smoke Evacuation or Fire Shut-
down mode (Display shows 35 or 37)
Minimum inverter set point too low
(VAV units only)
No fan status
Heat coil valve (HCV) is forced closed
NO hot water or steam available,
no power if electric heat
Electric heater safety tripped
No power to valve
No heat
No power to electric heater control
Incorrect reading from space temperature sensor,
supply-air temperature sensor, or return-air
temperature sensor (VAV units)
Configuration error
Heat coil valve (HCV) is forced open
Incorrect reading from space temperature sensor,
supply-air temperature sensor, or return-air
Overheating
temperature sensor (VAV units)
Configuration error
No fan status
Cooling coil valve (CCV) is forced closed
No chilled water available
No cooling
No power to cooling coil valve
Incorrect reading from space temperature sensor,
supply-air temperature sensor, or return-air
temperature sensor (VAV units)
Configuration error
Cooling coil valve (CCV) is forced open
Incorrect reading from space temperature sensor,
supply-air temperature sensor, or return-air
Overcooling
temperature sensor (VAV units)
Configuration error
LEGEND
CV — Constant Volume
VAV — Variable Air Volume

UNIT TROUBLESHOOTING

POSSIBLE CAUSE
113
CORRECTIVE ACTION
Check for correct power or blown fuses (F2).
Correct any deficiencies.
Check LEDs on control module (PSIO). If LED is not solidly
illuminated, check for loose connections. If all wires and
connectors are secure, replace PSIO module as described
on page 112.
Verify control shows correct time. If incorrect, enter correct
time.
Verify HOA switch is in the AUTO position.
Check low-temperature thermostat and high-pressure switch
(VAV units only). Reset switches if necessary.
Using the local interface device, exit Quick Test.
Press 5 TEST, and then ENTR to exit.
Verify that unit should be in the Demand Limit mode. If not,
cycle power to PIC to release unit from Demand Limit
mode.
Verify that unit should be in one of these modes. If not,
check for shorted input on Fire Shutdown or Evacuation.
Adjust minimum to 20% at 4 mA signal and 100% at 20 mA
signal.
Check status of SFS (4 STAT). If SFS is OFF, check supply
fan status switch for proper operation. Switch must be ON
for heat coil to function properly.
Check status of HCV (5 STAT). If HCV is forced, remove
force and check operation.
Check source and correct any problems found.
Reset heater safety. Check for proper operation.
Check for blown fuse (F6). Replace if necessary. If fuse
is intact, check for proper connections. Check transformer
output.
Check for blown fuse (F5). Replace if necessary. If fuse
is intact, check for proper connections. Check transformer
output.
Check status of sensor readings for accuracy.
Replace sensor if defective.
Check configuration for proper heating set point and
Submaster Gain (SMG). An improper SMG can cause the
heating valve to be held closed.
Check status of HCV (5 STAT). If HCV is forced, remove
force and check operation.
Check status of sensor readings for accuracy. Replace
sensor if defective.
Check configuration for proper heating set point and
Submaster Gain (SMG). An improper SMG can cause the
heating valve to be held open.
Check status of SFS (4 STAT). If status is OFF, check
switch for proper operation. Supply fan status switch must
be ON for cooling coil to function properly.
Check status of CCV (5 STAT). If CCV is forced, remove
force and check operation.
Check source of chilled water. Correct any problems found.
Check for blown fuse (F3). Replace if necessary. If fuse
is intact, check for proper connections. Check transformer
output.
Check status of sensor readings for accuracy. Replace
sensor if defective.
Check configuration for proper cooling set point and
Submaster Gain (SMG). An improper SMG can cause the
CCV to be held closed.
Check status of CCV (5 STAT). If CCV is forced, remove
force and check operation.
Check status of sensor readings for accuracy. Replace
sensor if defective.
Check configuration for proper cooling set point and
Submaster Gain (SMG). An improper SMG can cause the
CCV to be held open.