Lennox MCC Series

Installation - Operation - Maintenance manual (IOM) • AIR COOLED CHILLERS & SPLIT UNITS - 1106-E • 37 •
8.1 LIST OF THE MOST COMMON PROBLEMS – CONTINUED
PROBLEMS – SYMPTOMS PROBABLE CAUSE RECOMMENDED ACTION
F) THE COMPRESSOR CUTS OUT ON ANTIFREEZE PRESSURE SWITCH
- Antifreeze pressure switch tripped
- Check that the pressure switch is
operating properly
- Low water flow in the evaporator - Check the water pump
- Evaporator obstructed
- Determine the degree of fouling by
measuring water pressure drop
- Evaporator frozen up
- Measure pressure drop in water
circuit, keep water circulating until
evaporator has thawed completely
- Low refrigerant charge
- Check the refrigerant charge and
add refrigerant if necessary
G) THE COMPRESSOR CUTS OUT ON ITS MOTOR PROTECTION THERMAL RELAY
- Thermal protection Tripped
- Check operation of thermal
protection, change it if necessary
- Motor windings are not being
sufficiently cooled
- Measure superheat in the
evaporator, adjust it if necessary
H) COMPRESSOR CUTS OUT THROUGH ACTION OF THE MAIN POWER FUSE
- Power supply on two phases only - Check power supply voltage
- Faulty motor windings - Replace the compressor
- Compressor seized - Replace the compressor
I) THE COMPRESSOR STARTS WITH DIFFICULTY
- Faulty windings - Replace the compressor
- Mechanical problem - Replace the compressor