Lennox EMEA HYDROLEAN, Installation, Operating And Maintenance, Page: 52 / 96

TROUBLESHOOTING – REPAIRS
CHILLER-IOM-2004-E
47
TROUBLESHOOTING – REPAIRS
1. LIST OF THE MOST COMMON PROBLEMS
PROBLEMS
– SYMPTOMS
PROBABLE CAUSE RECOMMENDED ACTION
A. THE COMPRESSOR DOES NOT START
• Motor control circuits established, the
compressor does not run
• No power supply • Check main power supply and switch
positions
• Compressor motor burnt out • Replace
• Low voltage reading on voltmeter • Voltage too low • Contact power company
• The system does not start • Breaker tripped or fuses blown • Determine the cause.
If the system is in running order, close
the disconnect
• Check condition of fuses
• No water flow in the evaporator or
condenser
• Measure flow, check the water pump
and water circuitry and filters
• Flow switch contacts open • Find the cause of the trip out
• Check circulation of liquid in
evaporator, and the condition of the
switch
• Anti short cycle relay action • Wait until the anti short cycle time
delay has expired
• Faulty control thermostat • Check for proper operation, set points,
contacts
• Oil pressure switch tripped
• Check the oil pressure switch and
determine the cause of the trip out
• Antifreeze thermostat or low
pressure safety switch tripped
• Check evaporating pressure, condition
of the antifreeze thermostat the low
pressure safety switch
• Compressor thermal protection relay
tripped
• Check for proper operation of the relay
• High pressure safety switch tripped • Check the condensing pressure, and
the condition of the high pressure
safety switch
• (if any) Low pressure safety switch
trip out
• Check low pressure safety switch
differential
• On MRC version, oil level too low
• Check the complete refrigerant circuits
and search for oil traps and design
mistakes
• Add oil
• Normal operation with too frequent
starts and stoppages due to action of
the low pressure safety switch. Bubbles
in sight glass.
• Or, normal compressor operation, but
the low pressure safety switch trops out
and resets frequently
• Low refrigerant charge • Check the charge through the Sight
glass on the liquid line, carry out a leak
test, then top up the refrigerant charge