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Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Catalog No. 04-53500046-01 Printed in U.S.A. Form 50VS-1SI Pg 22 311 11-08 Replaces: New
Copyright 2008 Carrier Corporation
has reached acceptable levels, the unit microprocessor will
power on automatically and resume previous operation.
LEAVING WATER TEMPERATURE SENSOR FAIL-
URE (LWT) — If the leaving water temperature thermistor
fails, it will not affect the operation of the unit. This sensor is
for monitoring purposes only.
DISCHARGE AIR TEMPERATURE SENSOR FAILURE
(DAT) — If the discharge temperature thermistor fails, it will
not affect the operation of the unit. This sensor is for monitor-
ing purposes only.
FREEZE PROTECTION 1 TEMPERATURE SENSOR
FAILURE (FP1) — If the freeze protection 1 thermistor fails
for 30 continuous seconds an FP1 lockout will occur. The
compressor will then be deenergized and the blower will deen-
ergize 15 seconds after the compressor is deenergized. The sen-
sor must be replaced if this lockout occurs.
FREEZE PROTECTION 2 TEMPERATURE SENSOR
FAILURE (FP2) — If the freeze protection 2 thermistor fails
for 30 continuous seconds an FP2 lockout will occur. The
compressor will then be deenergized and the blower will deen-
ergize 15 seconds after the compressor is deenergized. The sen-
sor must be replaced if this lockout occurs.
If unit performance during any mode appears abnormal, re-
fer to Table 13.
Table 13 — Troubleshooting
LEGEND
NOTE: Warning LEDs and error codes are found on the system con-
trol board.
FAULT DESCRIPTION
ERROR CODE
(COMMTSTAT)
SYSTEM WARNING (FLASH)
SYSTEM LOCKOUT (STEADY
ON)
POSSIBLE FAULT CAUSE
LED1 LED2 LED3 LED4 LED1 LED2 LED3 LED4
High Pressure Lockout
< 600 psi
Er 1 OFF OFF OFF FLASH OFF OFF OFF ON
Low Airflow (Heating), Low
Water Flow (Cooling)
Low Pressure Lockout
< 40 psi
Er 2 OFF OFF FLASH OFF OFF OFF ON OFF Low Refrigerant Charge
Freeze Protection, Air
Side
Er 4 OFF OFF FLASH FLASH OFF OFF ON ON
Water Temperature < 35 F
or < 15 F (Heating)
Freeze Protection, Air
Side < 35 F
Er 5 OFF FLASH OFF OFF OFF ON OFF OFF Blower Failure (Cooling)
Condensate Overflow Er 9, Er 10 OFF FLASH OFF FLASH OFF ON OFF ON Clogged Drain Line
Over/Under Low Voltage
Protection, 18-vac >
voltage, 30-vac
Er 11 OFF FLASH FLASH OFF OFF ON ON OFF Loss of Power, Brown Out
LWT Sensor Failure (Low
Water Temperature)
Er 13 FLASH OFF OFF OFF N/A N/A N/A N/A
Sensor Resistance Above
or Below Specification
DAT Sensor Failure
(Discharge Air
Temperature)
Er 14 FLASH OFF OFF FLASH N/A N/A N/A N/A
Sensor Resistance Above
or Below Specification
FP1 Sensor Failure
(Freeze Protection)
Er 15 FLASH OFF FLASH OFF ON OFF ON OFF
Sensor Resistance Above
or Below Specification
FP2 Sensor Failure
(Freeze Protection)
Er 16 FLASH OFF FLASH FLASH ON OFF ON ON
Sensor Resistance Above
or Below Specification
LED — Light-Emitting Diode