Carrier 40UV Installation, Start-Up And Service Instructions Manual page 70

PROBLEM
Unit Does Not Operate Power to control is OFF
Remote Start/Stop (S/S) jumper not installed (for
stand-alone operation only)
Faulty connections
Control switch is in OFF position or safety controls
are tripped
Smoke or fire detector is tripped, detector wiring
shorted
No Heating Heating is forced disabled
No hot water/steam/electricity
Electric heater safety tripped
Configuration error
No power to valve or relays
End switch improperly set (on Face and Bypass
units only)
Incorrect sensor reading
No fan status
No Cooling Cooling is forced disabled
No chilled water/electricity
Condensing unit safety tripped
Configuration error
No power to valve or relays
Outdoor air temperature below DX outdoor air lock-
out
End switch improperly set (on Face and Bypass
units only)
Incorrect sensor reading
No fan status
Overheating Heat outputs are forced
Configuration error
Overcooling Cooling outputs are forced
Configuration error
Mixed Air Damper Will Dampers are forced
Not Operate
No power to actuator
Configuration error
Failed sensor (shortened or open)
No fan status
Damper Fails to Operate Incorrectly calibrated sensors
Properly at Minimum
Position
Temperature Sensor Not Loose connections
Reading Correctly
Sensor out of calibration
Table 30 — Unit Diagnostics And Troubleshooting
POSSIBLE CAUSE
Check local disconnect or circuit breaker.
Install jumper between T20 on control module and TB
(24 vac).
Check LED on control board. If not flashing at a 1-second
rate, check for loose connections and 24 vac on POWER
connector.
Verify control switch is in the AUTO or CONT position.
Check for a tripped LLT.
Check the status of the Fire Shutdown input. Determine
cause of detector trip and correct if necessary. Check for
shorted wiring and correct if necessary.
Verify no forces are present in the Heating 1, Heating 2 or
Heating Enable outputs; remove if necessary.
Check source and correct any problems.
Determine cause for safety trip, typically insufficient air-
flow. Correct condition and reset safety switch in heater
control box.
Verify the control is configured properly for the type of
heat used.
Check for 24 vac at water valve. If no power, check for
open wiring.
Refer to Face and Bypass Damper testing to verify proper
operation of end switch and water valves.
Verify the temperature sensors are reading the correct
temperatures.
Verify the Fan Status reads ON. Fan Status must read ON
for heat to operate.
Verify no forces are present in the Cooling 1, Cooling 2 or
Heating Enable outputs; remove if necessary.
Check source and correct any problems.
Determine cause for safety trip, correct condition and
reset safety switch in condensing unit control box.
Verify the control is configured properly for the type of
cooling used.
Check for 24 vac at water valve. If no power, check for
open wiring.
Verify DX Outdoor Air Lockout is correctly set to the mini-
mum recommended condensing unit operating tempera-
ture. Verify OAT sensor is reading correctly.
Refer to Face and Bypass Damper Tests to verify proper
operation of end switch and water valves.
Verify the temperature sensors are reading the correct
temperatures.
Verify the Fan Status reads ON. Fan Status must read ON
for cooling to operate.
Verify no forces are present on the Heating 1 or Heating 2
outputs. Remove if necessary.
Verify the control is configured properly for the type of
heating used.
Verify no forces are present on the Cooling 1 or Cooling 2
outputs. Remove if necessary.
Verify the control is configured properly for the type of
cooling used.
Verify no forces are present on the MIX1 or MIX2 outputs.
Remove if necessary.
Check for 24 vac. If no power, check for open wiring.
Verify the control is properly configured for modulating
type OA damper.
Verify the temperature sensors are reading correctly.
Replace any bad sensor.
Verify the Fan Status reads ON. Fan Status must read ON
for dampers to operate.
Verify sensors are properly calibrated (refer to the test
section and repeat the calibration procedure). Verify no
forces are present on MAT, OAT, or SPT.
Verify all sensor lead connections are securely fastened.
Recheck each sensor reading using a digital thermometer
as a reference. Reset the TRIM value to zero before test-
ing each sensor (OAT, MAT, and RAT/SPT). Replace any
sensor requiring more than 5 degrees of correction.
70
CORRECTIVE ACTION