Operating instructions

19
XVIII. TROUBLESHOOTING GUIDE FOR LOCKOUT CONDITIONS
If the heat pump goes into lockout on a high or low pressure switch or discharge refrigerant temperature, the cause of the
lockout can be narrowed down by knowing the operating mode and which switch the unit locked out on. The following table
will help track down the problem once this information is known.
Note – A lockout condition is a result of the heat pump
shutting itself off to protect itself, never bypass the lockout circuit. Serious damage can be caused by the system operating
without lockout protection.
INDICATOR LIGHTS
CONDITION
PWR
ASC
LP
HP
DT
COMMENTS
AC power applied
Off
Off
Off
Off
Off
Blown fuse or power removed or loose fuse clips.
AC power applied
X
X
ASC indicator on for 4' 35" on power initialization.
AC power applied
X
Power applied - unit running or waiting for a call to run.
Run cycle complete
X
X
ASC indicator ON for 70 to 130 seconds after compressor shutdown.
LOW PRESSURE INDICATOR
Heating or Cooling – before
Y call
X
X
Flash
-Check if Low Pressure switch is open.
-Check electrical connections between Low Pressure switch and Controller.
Heating - during Y call
X
X
X
-Loss/lack of flow through ground-side heat exchanger.
-Low fluid temperature operation in ground-side heat exchanger.
-Freezing fluid in ground-side heat exchanger (lack of antifreeze).
-Dirty (fouled) ground-side heat exchanger (on ground water systems).
-Low ambient temperature at the heat pump.
-Increase time delay for #2 compr on “2-compressor” units to 60 seconds.
-Undercharged / overcharged refrigerant circuit.
-Expansion valve / sensing bulb malfunction.
-Excessive low fluid temperature in the hydronic-side heat exchanger.
Cooling - during Y call
X
X
X
-Loss/lack of flow through hydronic heat exchanger.
-Low fluid temperature in the hydronic loop.
-Freezing fluid in the hydronic heat exchanger (lack of antifreeze).
-Low ambient temperature at the heat pump.
-Increase time delay for #2 compr on “2-compressor” units to 60 seconds.
-Undercharged / overcharged refrigerant circuit.
-Expansion valve / sensing bulb malfunction.
-Excessively low fluid temperature in the ground side heat exchanger.
HIGH PRESSURE INDICATOR
Heating or Cooling – before
Y call
X
X
-Check if High Pressure switch is open.
-Check electrical connections between High Pressure switch and Controller.
Heating - during Y call
X
X
X
-Loss/lack of flow through hydronic heat exchanger.
-High fluid temperature in the hydronic loop.
-Overcharged refrigerant circuit.
-Expansion valve / sensing bulb malfunction.
Cooling – during Y call
X
X
X
-Loss/lack of flow through the ground-side heat exchanger.
-High fluid temperature in the ground-side heat exchanger.
-Dirty (fouled) ground-side heat exchanger (on ground water systems).
-Overcharged refrigerant circuit.
-Expansion valve / sensing bulb malfunction.
DISCHARGE REFRIGERANT TEMPERATURE INDICATOR (DT)
Heating or Cooling – before
Y call
X
X
-Check if DT switch is open.
-Check electrical connections between DT switch and Controller.
Heating - during Y call
X
X
X
-Significantly low flow through hydronic side and / or ground-side heat exchanger.
-Above maximum hydronic and / or below minimum ground temperatures.
-Significantly undercharged refrigerant circuit.
Cooling – during Y call
X
X
X
-Significantly low flow through hydronic side and / or ground-side heat exchanger.
-Above maximum ground and / or below minimum hydronic temperatures.
-Significantly undercharged refrigerant circuit.