Troubleshooting
Troubleshooting
Table G: Technical Diagnosis
Fault Description
Error Code
(commtstat)
System Warning (Flash) System Lockout (Steady On)
Possible Fault Cause
LD1 LD2 LD3 LD4 LD1 LD2 LD3 LD4
High pressure lockout
> 600 psig
ER 1 Off Off Off Flash Off Off Off On
Low air flow (heating)
Low water flow (cooling)
Low pressure lockout
< 40 psig
ER 2 Off Off Flash Off Off Off On Off Low refrigerant charge
Freeze protection
H
2
O 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 < 30VAC
ER 11 Off Flash Flash Flash Off On On On 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
57
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