44
Diagnostics
9.0 DIAGNOSTICS & TROUBLESHOOTING
9.9 Service Analyzer Charts (cont.)
CONTAMINATION
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
Reclaim refrigerant, evacuate, and recharge.
Unusual head and
suction readings
Wrong refrigerant or mixed refrigerants
Reclaim refrigerant, evacuate, and recharge.
Foreign matter –
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Copper tubing cuttings
Reclaim refrigerant, evacuate, and recharge.
Copper oxide
Dirty copper piping or nitrogen not used when
brazing
Reclaim refrigerant, evacuate, and recharge.
Welding scale
Nitrogen not used during brazing
Reclaim refrigerant, evacuate, and recharge.
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Reclaim refrigerant, evacuate, and recharge.
Excess soft solder
Wrong solder material
Reclaim refrigerant, evacuate, and recharge.
LOSS OF LUBRICATION
SYMPTOM
POSSIBLE CAUSE
REMEDY
Compressor failures
Vapor 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.
Low load
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Dirty coil
Wrong duct size
Restricted duct
Thermostat setting
Advise customer.
Short cycling of
compressor
Cycling or faulty high or low-pressure control
Check pressure and address cause of high or low pres-
sure. Replace control if faulty.
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.
TXV hunting when
running
Faulty TXV
Replace TXV.