York YR TB TB T0 - Page 72

JOHNSON CONTROLS
72
FORM 160.81-NOM1
ISSUE DATE: 10/3/2020
SECTION 6 – TROUBLESHOOTING
TABLE 18 – OPERATING ANALYSIS CHART (CONT'D)
RESULTS POSSIBLE CAUSE REMEDY
2. SYMPTOM: ABNORMALLY LOW SUCTION PRESSURE
Temperature di󰀨erence between leaving
chilled water and refrigerant in evapora-
tor greater than normal with high discharge
temperature.
Insu󰀩cient charge of refrigerant. Check for leaks and charge refrigerant into
system.
Flow orice blocked. Remove obstruction.
Temperature di󰀨erence between leaving
chilled water and refrigerant in the evaporator
greater than normal with normal discharge
temperature.
Evaporator tubes dirty or
restricted.
Clean evaporator tubes.
Temperature of chilled water too low with with
low motor amperes.
Insu󰀩cient load for system
capacity.
Check slide valve operation and setting of
low water temperature cutout.
3. SYMPTOM: HIGH EVAPORATOR PRESSURE
High chilled water temperature.
Slide valves fail to open. Check the slide valve solenoid valve.
System overload. Be sure the vanes are loaded (without
overloading the motor) until the load
decreases.
4. SYMPTOM: COMPRESSOR STARTS, NORMAL OIL PRESSURE DEVELOPS, FLUCTUATES FOR SHORT WHILE,
THEN COMPRESSOR STOPS ON OIL PRESSURE CUTOUT
Oil pressure normal, uctuates then
compressor stops on Oil Pressure Cutout.
Display reading
LOW OIL PRESSURE
Unusual starting conditions
exist, i.e., oil foaming in
reservoir and piping due to
lowered system pressure.
Drain the oil from the oil separator and
charge new oil into the oil separator.
Burned out oil heater. Replace oil heater.
5. SYMPTOM: OIL PRESSURE GRADUALLY DECREASES (Noted by Observation of Daily Log Sheets)
Oil pressure (noted when pressing
OIL PRESSURE display key) drops to
70% of oil pressure when compressor was
originally started.
Oil lter is dirty. Change oil lter.
Extreme bearing wear. Inspect compressor.
6. SYMPTOM: OIL RETURN SYSTEM CEASES TO RETURN AN OIL/REFRIGERANT SAMPLE
Oil refrigerant return not functioning.
Strainer in oil return system
dirty.
Replace old strainer with new.
Jet or orice of oil return jet
clogged.
Remove jet, inspect for dirt. Remove dirt
using solvent and replace.
7. SYMPTOM: SYSTEM FAILS TO DELIVER OIL PRESSURE
No oil pressure registers when pressing
OIL PRESSURE display key.
Faulty oil pressure transducer.
Faulty wiring/connectors.
Replace oil pressure transducer.
8. SYMPTOM: LOW DISCHARGE SUPERHEAT WARNING MESSAGE
Low Discharge Superheat
Over charged with refrigerant. Adjust charge.
Refrigerant saturated with oil. Perform oil recovery and check oil levels.
Variable Orice not functioning
properly.
Repair or adjust Variable Orice.
Refrigerant level set incorrectly. Raise refrigerant level set point.