Troubleshooting
Table 1: Operation analysis chart
Results Possible cause Remedy
1. Symptom: abnormally high discharge pressure
The temperature difference between the
condensing temperature and water off condenser
is higher than normal.
Air is in the condenser.
Condenser tubes dirty or scaled.
Clean condenser tubes. Check water
conditioning.
High discharge pressure.
High condenser water
temperature.
Reduce condenser water inlet
temperature.
Check cooling tower and water
circulation.
Temperature difference between condenser water
on and water off higher than normal, with normal
evaporator pressure.
Insufficient condensing water
flow.
Increase the quantity of water
through the condenser to proper
value.
2. Symptom: abnormally low suction pressure
Insufficient charge of refrigerant.
Check for leaks and charge
refrigerant into system.
Temperature difference between leaving chilled
water and refrigerant in evaporator greater than
normal with high discharge temperature.
Variable orifice problem. Remove obstruction.
Temperature difference 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 low
motor amperes.
Insufficient load for system
capacity.
Check pre-rotation vane motor
operation and setting of low water
temperature cutout.
3. Symptom: high evaporator pressure
Pre-rotation vanes fail to open.
Check the pre-rotation vane motor
positioning circuit.
High chilled water temperature.
System overload.
Be sure the vanes are wide open
(without overloading the motor)
until the load decreases.
4. Symptom: no oil pressure when system start button pushed
Oil pump running in wrong
direction.
Check rotation of oil pump (Electrical
Connections).
Low oil pressure displayed on control center;
compressor does not start.
Oil pump not running.
Troubleshoot electrical problem with
oil pump VSD.
5. Symptom: unusually high oil pressure develops when oil pump runs
Unusually high oil pressure is displayed when the
oil pressure display key is pressed when the oil
pump is running.
High oil pressure. Transducer
defective.
Replace low or high oil pressure
transducer.
6. Symptom: oil pump vibrates or is noisy
Oil not reaching pump suction
inlet in sufficient quantity.
Check oil level.
Oil pump vibrates or is extremely noisy with some
oil pressure when pressing OIL PRESSURE display
key.
Note: When oil pump is run without an oil
supply, it vibrates and becomes extremely
noisy.
Worn or failed oil pump. Repair/Replace oil pump.
7. Symptom: reduced oil pump capacity
Excessive end clearance pump.
Other worn pump parts.
Inspect and replace worn parts.
Oil pump pumping capacity.
Partially blocked oil supply inlet. Check oil inlet for blockage.
8. Symptom: oil pressure gradually decreases (noted by observation of daily log sheets)
When the oil pump VSD frequency increases to 55 +
Hz to maintain target oil pressure.
Oil filter is dirty. Change oil filter.
Model YK (Style H), R-134a and R-513A26
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