Lennox MCC Series Installation, Operating And Maintenance

Installation - Operation - Maintenance manual (IOM) • AIR COOLED CHILLERS & SPLIT UNITS - 1106-E • 39 •
8.1 LIST OF THE MOST COMMON PROBLEMS – CONTINUED
PROBLEMS – SYMPTOMS PROBABLE CAUSE RECOMMENDED ACTION
M) SUCTION PRESSURE IS TOO HIGH
- The compressor runs
continuously
- Too much cooling demand on the
evaporator
- Check the system
a) Expansion valve opened to far
a) Adjust superheat and check that
the expansion valve bulb is
correctly fitted in place
- Suction line unusually cold.
Liquid refrigerant returns to
compressor
b) Expansion valve blocked in open
position
b) Repair or replace
N) SUCTION PRESSURE IS TOO LOW
- Bubbles in sightglass - Low refrigerant charge - Repair the leak and add refrigerant
- Excessive pressure drop across the
filter-drier or the solenoid valve
- Filter-drier obstructed - Replace the cartridge
- No refrigerant passing through the
expansion valve
- Expansion valve bulb has lost its
charge.
- Replace the bulb
- Loss of capacity - Expansion valve obstructed - Clean or replace
- Conditioned space too cold
- Control thermostat contacts stuck in
closed position
- Repair or replace
- Compressor short-cycling - Capacity modulation setting too low - Adjust
- Superheat value too high
- Excessive pressure drop in the
evaporator
- Check the external equalizing line
on the expansion valve
- Low pressure drop in the evaporator - Low water flow
- Check water flow. Check the
condition of the filters, look for
obstructions in the chilled water
circuit piping

Lennox MCC Series Specifications

General

Brand	Lennox
Model	MCC Series
Category	Chiller
Language	English