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10.0 DIAGNOSTICS & TROUBLESHOOTING
10.7
Service Analyzer Chart (cont.)
Diagnostics
CONTAMINATION
SYMPTOM POSSIBLE CAUSE CHECK/REMEDY
Moisture Poor evacuation on installation or during service
In each case, the cure is the same. Recover re-
frigerant. Add lter drier, evacuate and recharge
High head pressure Noncondensibles air
Unusual head and
suction readings
Wrong refrigerant or mixed refrigerants
Foreign matter - copper
lings
Copper tubing cuttings
Copper oxide Dirty copper piping or nitrogen not used when brazing
Welding scale Nitrogen not used during brazing
Soldering ux Adding ux before seating copper partway
Excess soft solder Wrong solder material
LOSS OF LUBRICATION
SYMPTOM POSSIBLE CAUSE CHECK/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 com-
pressor
Flooding Check system charge
Low load
Reduced airow Dirty lter
Dirty coil
Wrong duct size
Restricted duct
Thermostat setting Advise customer
Short cycling of com-
pressor
Cycling or faulty high or low-pressure control Check pressures and address cause of any
abnormal pressure. Replace control if faulty
Loose wiring Check all control wires
Thermostat In supply air stream, out of calibration
Customer misuse
SLUGGING
SYMPTOM POSSIBLE CAUSE CHECK/REMEDY
On start-up Incorrect piping Review pipe size guidelines
TXV hunting when
running
Fault TXV Replace TXV
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