Operating instructions

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XII. TROUBLESHOOTING GUIDE FOR LOCKOUT CONDITIONS
If the heat pump goes into lockout on a high or low pressure switch, the cause of the lockout can be narrowed down by
knowing the operating mode and which pressure 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.
MODE LOCKOUT CONDITION POSSIBLE CAUSE
High Pressure
(Condenser/Hydronic Side)
-Loss/lack of flow through hydronic heat exchanger
-High fluid temperature operation in the hydronic loop
-Overcharged refrigerant circuit Heating
Low Pressure
(Evaporator/Earth Coupled Side)
-Loss/lack of flow through earth coupled coil
-Low fluid temperature operation in the earth loop
-Freezing fluid in heat exchanger (lack of antifreeze)
-Undercharged/overcharged refrigerant circuit
-Expansion valve/sensing bulb malfunction
High Pressure
(Condenser/Earth Coupled Side)
-Loss/lack of flow in earth loop
-High fluid temperature operation in the earth loop
-Dirty (fouled) condenser coil
-Overcharged refrigerant circuit Cooling
Low Pressure (Anti-Short Cycle)
(Evaporator/Hydronic Side)
-Loss/lack of flow through hydronic heat exchanger
-Low fluid temperature operation in the hydronic loop
-Freezing fluid in hydronic heat exchanger (lack of antifreeze)
-Undercharged/overcharged refrigerant circuit
-Expansion valve/sensing bulb malfunction
XIII. TROUBLESHOOTING GUIDE FOR UNIT OPERATION
PROBLEM POSSIBLE CAUSE CHECKS AND CORRECTIONS
Blown Fuse/Tripped Circuit
Breaker
Replace fuse or reset circuit breaker. (Check for correct size fuse or circuit
breaker.)
Blown Fuse on Controller Replace fuse on controller. (Check for correct size fuse.)
Broken or Loose Wires Replace or tighten the wires.
Voltage Supply Low If voltage is below minimum voltage on data plate, contact local power company.
Low Voltage Circuit Check 24-volt transformer for burnout or voltage less than 18 volts.
Thermostat Set thermostat on "Cool" and lowest temperature setting, unit should run. Set
thermostat on "Heat" and highest temperature setting, unit should run. If unit does
not run in both cases, the thermostat could be wired incorrectly or be faulty. To
prove faulty or miswired thermostat, disconnect thermostat wires at the unit and
jumper between "R", "Y" and "G" terminals and unit should run. Replace
thermostat with correct thermostat only. A substitute may not work properly.
Entire unit does not
run.
Interruptible Power Check incoming supply voltage.
Water Lack of sufficient pressure, temperature and/or quantity of water.
Unit Undersized Recalculate heat gains or losses for space to be conditioned. If excessive, rectify
by adding insulation, shading, etc.
Loss of Conditioned Air by Leaks Check for leaks in ductwork or introduction of ambient air through doors and
windows.
Thermostat Improperly located thermostat (e.g. near kitchen sensing inaccurately the comfort
level in living areas). Check anticipator setting (Should be 1.0 or 1.2).
Insufficient cooling or
heating
Airflow (Across fan coil) Lack of adequate airflow or improper distribution of air. Check the motor speed
and duct sizing. Check the filter, it should be inspected every month and changed
if dirty. Remove or add resistance accordingly.
Refrigerant Charge Low on refrigerant charge causing inefficient operation. Adjust only after
checking CFM and GPM.
Compressor Check for defective compressor. If discharge pressure is too low and suction
pressure too high, compressor is not pumping properly. Replace compressor.
Reversing Valve Defective reversing valve creating bypass of refrigerant from discharge to suction
side of compressor. When it is necessary to replace the reversing valve, wrap it
with a wet cloth and direct the heat away. Excessive heat can damage the valve.
Desuperheater The desuperheater circuit (in-line fuse) should be disconnected during cold
weather to allow full heating load to house.