214
IM 1167
Troubleshooting Chart
Low Suction
Pressure
1.
Inadequate refrigerant charge quantity.
2.
Clogged liquid line filter-drier.
3.
Expansion valve malfunctioning.
4.
Insufficient water flow to evaporator.
5.
Water temperature leaving evaporator is too low.
6.
Evaporator tubes fouled.
7.
Suction valve (partially) closed.
8.
Glycol in chilled water system
1.
Check liquid line sight glass. Check unit for leaks. Repair and
recharge to clear sight glass at full load, all fans on, 75
F min OAT..
2.
Check pressure drop across the filter-drier. Replace filter-driers.
3.
Check expansion valve superheat and valve opening position.
Replace valve only if certain valve is not working.
4.
Check water pressure drop across the evaporator and adjust gpm.
5.
Adjust water temperature to higher value.
6.
Inspect by removing water piping. Clean chemically.
7.
Open valve.
8.
Check glycol concentration
Low Oil Level Trip
1.
Insufficient oil.
2.
Low discharge pressure.
3.
Low discharge superheat
1.
Check oil line and separator sight glasses.
2.
Faulty EXV.
3.
Check and correct cause of low DSH
High Suction
Pressure
1.
Excessive load - high water temperature.
2.
Compressor unloaders not loading compressor.
3.
Superheat is too low.
4.
System overcharged
5.
Compressor bypassing gas
1.
Reduce load or add additional equipment.
2.
See corrective steps below for failure of compressor to load.
3.
Check superheat on Microtech III display. Check suction line sensor
installation and sensor.
4.
Check charge, an overcharge raises suction pressure
5.
Check evaporator, suction and discharge pressures
Table 123: Troubleshooting Chart