40
DIAGNOSTICS
Service Analyzer Charts
SYMPTOM POSSIBLE CAUSE REMEDY
Moisture Poor evacuation on installation or during service In each case, the cure is the same. Recover refrigerant.
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High head pressure Noncondensibles air
Unusual head and
suction readings
Wrong refrigerant or mixed refrigerants
Foreign matter –
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Copper tubing cuttings
Copper oxide Dirty copper piping or nitrogen not used when
brazing
Welding scale Nitrogen not used during brazing
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Excess soft solder Wrong solder material
LOSS OF LUBRICATION
SYMPTOM POSSIBLE CAUSE REMEDY
Compressor failures Line tubing too large Reduce pipe size to improve oil return.
Low suction pressure Low charge Check system charge.
Refrigerant leaks Repair and recharge.
Cold, noisy
compressor –
Slugging
Dilution of oil with refrigerant Observe piping guidelines.
Noisy compressor Migration Check crankcase heater.
Cold, sweating
compressor
Flooding Check system charge.
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Dirty coil
Wrong duct size
Restricted duct
Thermostat setting Advise customer.
Short cycling of
compressor
Faulty high- or low-pressure control Replace control.
Loose wiring Check all control wires.
Thermostat In supply air stream, out of calibration
Customer misuse
SLUGGING
SYMPTOM POSSIBLE CAUSE REMEDY
On start-up Incorrect piping Review pipe size guidelines.
TEV hunting when
running
Faulty TEV Replace TEV.
CONTAMINATION
Diagnostics