160.78-O1 — YMC2 Mod A Centrifugal Chiller with OptiView Control Center, Unit Operation Guide

Document type	Operation Guide
Document number	160.78-O1
Equipment	YMC2 Magnetic Bearing Centrifugal Chiller
Brand	YORK
Revised	2025-04-25
File size	1.5 MB

Fault codes in this document

Compressor

Code / display	Meaning	Cause	Action	Page
Control panel warns of excessive landings of the magnetic bearing motor			Notify the nearest Johnson Controls office to request the presence of a Johnson Controls Service Technician. The technician can assess the condition of the touchdown bearings using electronic tools.	22

Symptom: abnormally high discharge pressure

Code / display	Cause	Action	Page
Temperature difference between condensing temperature and water off condenser higher then normal	Condenser tubes dirty or scaled	• Clean condenser tubes • Check water conditioning	24
Temperature difference between condensing temperature and water off condenser higher then normal	Condenser tubes dirty or scaled	• Clean condenser tubes • Check water conditioning	24
High discharge pressure	High condenser water temperature	• Reduce condenser water inlet temperature • Check cooling tower and water circulation	24
Temperature diffrence between condenser water on and water off higher than normal, with normal discharge temperature	Insufficient condensing water flow	Increase the quantity of water through the condenser to the correct value	24

Symptom: abnormally low suction pressure

Code / display	Cause	Action	Page
Temperature difference between leaving chilled water and refrigerant in the evaporator greater than normal with normal discharge temperature.	Variable orifice problem	Remove obstruction	24
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	24
Temperature of chilled water too low with low motor amperes	Insufficient load for system capacity	Check capacity control operation and setting of low water temperature shutdown setpoint	24

Symptom: high evaporator pressure

Code / display	Meaning	Cause	Action	Page
High chilled water temperature		System overload	Ensure that the capacity control devices and speed increased (without overloading the motor) until the load decreases	24

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 YMC2 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.