Trane Manhattan Gen II Installation, Operation And Maintenance Manual page 64

Chiller Troubleshooting
7. Symptom: Low refrigeration suction pressure (continued)
Possible Causes
Low water temperature
Compressor will not unload
Low discharge pressure
Expansion valve malfunctioning
Mis-adjusted or defective TXV
Receiver service valve closed
Compressor service valves closed
Clogged liquid line filter-drier
Excessive glycol concentration
Liquid line solenoid restricted or faulty
Insufficient chilled water
Restricted water/glycol line
Water/glycol mixture contaminated
Evaporator tubing clogged or fouled
8. Symptom: High refrigeration suction pressure
Possible Causes
Expansion valve opened too far
Excessive refrigerant charge
High water temperature
9. Symptom: Low refrigerant discharge pressure
Possible Causes
Suction shut off valve partially closed
Insufficient refrigerant in chiller
Compressor operating unloaded
Low ambient conditions
Low suction pressure
Condenser pressure regulating valve not properly adjusted
Fan cycling controls not properly set
10. Symptom: High refrigerant discharge pressure
Possible Causes
System overcharged with refrigerant
Dirty tube and fin surface
Non-condensables in chiller
Fan cycling controls not properly set
Condensing fans not operating
Restricted bypass line
Discharge shut off valve partially closed
Condenser is undersized
High ambient conditions exist
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Potential Solutions
Raise set point; check design specification
Replace solenoid or controller
Refrigerant charge; replace compressor
Reset for proper superheat (10-12 º SH)
Adjust or replace valve
Turn counterclockwise completely. Do not fully backseat if pressure
switch is installed on service port
Dangerous! Turn counterclockwise completely
Replace cartridges
Drain, refill (deionized water), retest
Replace solenoid valve, coil, or internals as necessary
Adjust flow rate across evaporator
Clean strainers; check manual and electronic valves
Intensive cleanup effort needed to identify source of contamination;
external filter may be required
Reverse flush with appropriate chemical solutions
Potential Solutions
Re-adjust to 10° to 12°
Creates high pressure alarms; reclaim excess refrigerant and verify
proper sub-cooling and superheat.
Low refrigerant charge; failing compressor; check design specifications
Potential Solutions
Open valve
Check for leaks. Repair and add refrigerant as needed
See failure of compressor to unload or load up below
Check condenser rating tables
See low pressure below
Refer to OEM manufacturer manual for default settings; check equipment
room ambient temperature
Reset cut-in, cut-out settings to conform to design specifications
Potential Solutions
Remove excess refrigerant
Clean with compressed air or water spray, use fin comb if fins are bent
Purge non-condensables.
Reset fan cycle setting; replace motor controller fuse
Reset fan cycle setting; replace motor controller fuse
Check valves obstructed; flush line; blow out line with dry nitrogen gas
Open valve
Check condenser rating tables with operating parameters
Check condenser rating tables with operating parameters
ARTC-SVX002A-EN