| Document type | Operation Guide |
|---|---|
| Document number | 160.95-O1 |
| Equipment | YK Centrifugal Chiller |
| Brand | YORK |
| Revised | 2026-01-21 |
| File size | 9.1 MB |
Fault codes in this document
4 of these messages are explained on a page of their own — cause, what to check, reset — written from this manual:
Troubleshooting — Table 4: Operation analysis chart
| Code / display | Meaning | Cause | Action | Page |
|---|---|---|---|---|
| 1. Issue: abnormally high discharge pressure | The temperature difference between the condensing temperature and water off condenser is higher than normal. | Air is in the condenser. | 34 | |
| 1. Issue: abnormally high discharge pressure | The temperature difference between the condensing temperature and water off condenser is higher than normal. | Condenser tubes dirty or scaled. | Clean condenser tubes. Check water conditioning. | 34 |
| 1. Issue: abnormally high discharge pressure | High discharge pressure. | High condenser water temperature. | Reduce condenser water inlet temperature. Check cooling tower and water circulation. | 34 |
| 1. Issue: abnormally high discharge pressure | The temperature difference between condenser water on and water off is higher than normal, with normal evaporator pressure. | Insufficient condensing water flow. | Increase the quantity of water through the condenser to proper value. | 34 |
| 2. Issue: abnormally low suction pressure | Insufficient charge of refrigerant. | Check for leaks and charge refrigerant into system. | 34 | |
| 2. Issue: abnormally low suction pressure | The temperature difference between the leaving chilled water and the refrigerant in the evaporator is greater than normal with high discharge temperature. | Variable orifice problem. | Remove obstruction. | 34 |
| 2. Issue: abnormally low suction pressure | The temperature difference between the leaving chilled water and the refrigerant in the evaporator is greater than normal with normal discharge temperature. | Evaporator tubes dirty or restricted. | Clean evaporator tubes. | 34 |
| 2. Issue: abnormally low suction pressure | The temperature of chilled water is too low with low motor amperes. | Insufficient load for system capacity. | Check the motor operation of the PRV and check the setting of the low water temperature cutout. | 34 |
| 3. Issue: high evaporator pressure | PRVs fail to open. | Check the PRV motor positioning circuit. | 34 | |
| 3. Issue: high evaporator pressure | High chilled water temperature. | System overload. | Ensure the vanes are wide open (without overloading the motor) until the load decreases. | 34 |
| 4. Issue: no oil pressure when system start button pushed | Low oil pressure is displayed on the control center; the compressor does not start. | Oil pump running in wrong direction. | Check rotation of oil pump (Electrical Connections). | 34 |
| 4. Issue: no oil pressure when system start button pushed | Low oil pressure is displayed on the control center; the compressor does not start. | Oil pump not running. | Troubleshoot electrical problem with oil pump VSD. | 34 |
| 5. Issue: 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. The transducer is defective. | Replace low or high oil pressure transducer. | 34 |
| 6. Issue: oil pump vibrates or is noisy | Oil pump vibrates or is extremely noisy with some oil pressure when pressing the Oil Pressure display key. Note: When the oil pump is run without an oil supply, it vibrates and becomes extremely noisy. | Oil not reaching pump suction inlet in sufficient quantity. | Check oil level. | 34 |
| 6. Issue: oil pump vibrates or is noisy | Oil pump vibrates or is extremely noisy with some oil pressure when pressing the Oil Pressure display key. | Worn or failed oil pump. | Repair or, if necessary, replace the oil pump. | 34 |
| 7. Issue: reduced oil pump capacity | Oil pump pumping capacity. | Excessive end clearance pump. Other worn pump parts. | Inspect and replace worn parts. | 34 |
| 7. Issue: reduced oil pump capacity | Oil pump pumping capacity. | The oil supply inlet is partially blocked. | Check the oil inlet for blockage. | 34 |
| 8. Issue: oil pressure gradually decreases as 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. | 34 |
| 9. Issue: oil pressure system ceases to return an oil/refrigerant sample | Oil refrigerant return not functioning. | Filter-drier in oil return system dirty. | Replace old filter-drier with new. | 34 |
| 9. Issue: oil pressure system ceases to return an oil/refrigerant sample | Oil refrigerant return not functioning. | Jet or orifice of oil return jet clogged. | Remove jet, inspect for dirt. Remove dirt using solvent and replace. | 34 |
| 10. Issue: oil pump fails to deliver oil pressure | No oil pressure registers when pressing the Oil Pressure display key when the oil pump runs. | Faulty oil pressure transducer. | Replace oil pressure transducer. | 35 |
| 10. Issue: oil pump fails to deliver oil pressure | No oil pressure registers when pressing the Oil Pressure display key when the oil pump runs. | Faulty wiring or connectors. | Replace oil pressure transducer. | 35 |
Safety shutdowns and warnings
| Code / display | Meaning | Cause | Action | Page |
|---|---|---|---|---|
| Leaving Chilled Liquid – Low Temperature Control | Safety control that shuts down the chiller. | The load continues to decrease, after the PRVs are entirely closed. | 15 | |
| oil pressure safety cutout | Actuates and stops the system. | Refrigerant boiling out of the oil as the pressure is lowered on starting causes violent oil foaming; if this foam reaches the oil pump suction, the bearing oil pressure fluctuates with possible temporary loss of lubrication. | Refer to OptiView Control Center – Operation Manual (160.76-O2). | 27 |
| high oil temperature (HOT) | The unit is shutting down on high oil temperature. | Incorrect lubrication, brought about by restricted oil lines, passages, or dirty oil filters. | Change the oil filter element. Examine the oil filter element for the presence of aluminum particles; if aluminum particles continue to accumulate, contact Johnson Controls Service. | 40 |
| low oil pressure (OP) | The unit is shutting down on low oil pressure. | Incorrect lubrication, brought about by restricted oil lines, passages, or dirty oil filters. | Change the oil filter element. Examine the oil filter element for the presence of aluminum particles; if aluminum particles continue to accumulate, contact Johnson Controls Service. | 40 |
| warning message to re-lubricate | OptiView panels provide a warning message to re-lubricate beginning at a programmed number of operating hours (the default value is 1000 hours). At the programmed value plus 400 hours this feature shuts down the chiller if re-lubrication is not addressed. | Programmed number of operating hours reached. | Re-lubricate the motor bearings; if re-lubrication is not addressed, the chiller shuts down at the programmed value plus 400 hours. | 43 |
| bearing temperature warning — 149°F (65°C) | If the temperature exceeds 149°F (65°C), a warning is issued. | Either the bearings are in need of lubrication or that something is wrong. | Operation should be checked. | 47 |
| bearing RTD shutdown — 194°F (90°C) | Bearing RTDs are normally set to shut down the motors at 194°F (90°C), although when this temperature is reached, the bearings most likely have already been compromised. | Motors shut down by bearing RTDs at 194°F (90°C). | 44 | |
| quarterly maintenance warning item | Monthly items appear on OptiView as a quarterly maintenance warning item. | Monthly items are still required. | Perform the monthly maintenance procedures. | 20 |
Every row above cites the page of this document it came from, and each one is re-read against that page by an automatic check before publication. The short table of all YORK YK messages: fault codes.
Manufacturer document, published here as reference material for equipment we supply. The original lives at docs.johnsoncontrols.com. The rights holder may ask us to take it down — we will.