Installation - Operation - Maintenance manual (IOM) • AIR COOLED CHILLERS & SPLIT UNITS - 1106-E • 36 •
8.1 LIST OF THE MOST COMMON PROBLEMS – CONTINUED
PROBLEMS – SYMPTOMS
PROBABLE CAUSE
RECOMMENDED ACTION
D) THE COMPRESSOR RUNS IN LONG CYCLES OR RUNS CONTINOUSLY
- Faulty control thermostat - Check operation
- Temperature too low in the
conditioned space
- Chilled water thermostat set too low - Adjust it
- Bubbles in sightglass - Low refrigerant charge
- Check the refrigerant charge in the
sightglass and top up if necessary
- Filtrer-drier partly obstructed
- Check the drier and replace as
required, change the filter cartridge
- Expansion valve partly closed
- Check expansion valve bulb and
capillary, measure superheat
- Liquid line valve not open far
enough
- Open the valve completely
- Noisy compressor, or abnormally
high suction pressure or low
discharge pressure
- Leaky compressor valves
- Check valve gas-tightness, replace
the valve plate if necessary. Tighten
compressor nuts and bolts
E) THE COMPRESSOR CUTS OUT ON OIL PRESSURE SAFETY SWITCH
- Oil pressure switch tripped
- Check operation of the oil pressure
safety switch
- Oil level in sightglass is too low - Oil pressure too low
- Check the oil level in the sightglass
on the crankcase, check the
cleanliness of the oil filter, check the
oil pump
- Visible oil leak / Oil level too low - Low oil charge
- Check that there is no leakage and
add oil
- Leaky oil sump - Repair and add oil
- Suction line unusually cold,
compressor noisy
- Liquid refrigerant present in the
compressor crankcase
- Check appearance of the oil in the
sightglass. Measure temperature of
the oil pump, measure superheat at
the expansion valve, check that the
valve bulb is tightly attached
- Poor heat exchange in the
evaporator
- Check water flow. Check fouling by
measuring the water pressure drop.
Excessive oil migration in the circuit
: measure evaporating pressure,
superheat and the temperature of
the oil pump
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