63
CONTAMINATION
SYMPTOM
POSSIBLE CAUSE
REMEDY
Moisture
Poor evacuation on installation or during service
In each case, the cure is the same.
Remove refrigerant. Add filter drier, evacuate, and recharge.
High head pressure Noncondensibles air
Unusual head and
suction pressure
readings
Wrong refrigerant or mixed refrigerants
Foreign matter-
copper filings
Copper tubing cuttings
Copper oxide
Dirty copper piping or nitrogen not used when brazing
Welding scale
Nitrogen not used during brazing
Soldering flux
Adding flux before seating copper partway
Excess soft solder
Wrong solder material
LOSS OF LUBRICATION
SYMPTOM
POSSIBLE CAUSE
REMEDY
Compressor failures
Suction 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 stater heat and compressor thermistor.
Cold, sweating
compressor
Flooding
Check system charge.
Low load
Reduced airflow
Dirty filter.
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 any abnormal pressure.
Replace control, if faulty.
Loose wiring
Check all control wires.
Thermostat
In supply air steam, out of calibration.
Customer misuse.
LIQUID REFRIGERANT SLUGGING
SYMPTOM
POSSIBLE CAUSE
REMEDY
On start-up
Incorrect piping
Review pipe size guidelines.
EXV hunting when
running
Faulty EXV components
Check EXV, suction pressure transducer, and suction thermistor
for operation.
9.0 DIAGNOSTICS & TROUBLESHOOTING
9.9 Service Analyzer Charts (cont.)
Diagnostics
