Installation - Operation - Maintenance manual (IOM) • AIR COOLED CHILLERS & SPLIT UNITS - 0105-E • 35 •
TROUBLESHOOTING - REPAIRS
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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