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