18
TROUBLESHOOTING
LEGEND
TXV —
Thermostatic Expansion Valve
Read Safety Considerations on page 1 before proceeding
with troubleshooting.
PROBLEM CAUSE REMEDY
Compressor does not run.
Main power line open. Replace fuse or reset circuit breaker.
Safety thermostat tripped. Reset thermostat.
Condenser water pump not running — power off. Restart.
Pump binding. Free pump.
Incorrect wiring. Rewire.
Motor burned out. Replace.
Control stuck open. Replace control.
Loose terminal connection. Check connections.
Improperly wired controls. Check wiring and rewire.
Low line voltage. Check line voltage — determine location of
voltage drop.
Compressor motor defective. Check motor winding for open or short.
Replace compressor if necessary.
Seized compressor. Replace compressor.
Compressor cycles on low-pressure
control.
Low-pressure control erratic in action. Raise differential setting, check capillary for
pinches, replace control.
Suction shutoff valve partially closed. Open valve.
Low refrigerant charge. Add refrigerant.
Plugged suction strainer. Clean strainer.
Defective TXV. Replace.
Compressor cycles on high-pressure
control.
High-pressure control erratic in action. Check capillary tube for pinches. Set control as
required.
Discharge valve partially closed. Open valve.
Air in system. Purge.
Condenser scaled (or airflow restricted). Clean condenser.
Receiver not properly vented, refrigerant backs
up into evap condenser.
Repipe as required.
Condenser water pump or fans not
operating.
Start pump or fans.
Refrigerant overcharge. Purge.
Insufficient capacity.
Low refrigerant charge. Add refrigerant.
Control set too high. Reset control.
Expansion valve plugged. Clean or replace.
Inefficient compressor. Check valves and pistons.
Expansion valve setting too high. Lower setting.
Iced or dirty evaporator. Defrost or clean.
Evaporator too small. Add surface or replace.
Condensing unit too small. Add unit or replace.
Expansion valve too small. Raise suction pressure with larger valve.
Restricted or small gas lines. Clear restriction or increase line size.
Unit operates long or continuously.
Low refrigerant charge. Add refrigerant.
Control contacts fused. Replace control.
Air in system. Purge.
Partially plugged or plugged expansion valve or
strainer.
Clean or replace.
Defective insulation. Replace or repair.
Service load. Keep doors and windows closed.
Inefficient compressor. Check valves.
Condenser scaled. Clean condenser.
Restricted evaporator air. Defrost coil, clean filters and ductwork.
