Hazardous Voltage - Pressurized Burning Fluid!
Failure to follow all electrical safety precautions could result in death or serious injury.
Compressors on 110 and 120 ton, extra efficiency units, have strong permanent magnet motors that have the capability to generate voltage during situations when the refrigerant charge is being migrated. This potential will be present at the motor terminals and at the load side of compressor contactors.
Before removing compressor terminal box cover for servicing, or servicing power side of control panel, CLOSE COMPRESSOR DISCHARGE SERVICE VALVE and disconnect all electric power including remote disconnects. Follow lockout/tagout procedures to ensure the power cannot be inadvertently energized.
The compressor contains hot, pressurized refrigerant. Motor terminals act as a seal against this refrigerant. Care should be taken when servicing NOT to damage or loosen motor terminals.
Do not operate compressor without terminal box cover in place.
Failure to disconnect power before servicing could result in death or serious injury. Disconnect all electric power, including remote disconnects before servicing. Follow proper lockout/tagout procedures to ensure the power can not be inadvertently energized.
Perform all maintenance procedures and inspection at the recommended intervals. This will prolong the life of the chiller and minimize the possibility of malfunctions.
Use an “Operator’s Log” to record the unit’s operating history. The log serves as a valuable diagnostic tool for service personnel. By observing trends in operating conditions, an operator can anticipate and prevent problem situations before they occur.
If the unit is not operating properly during maintenance inspections, see “Diagnostics,” p. 133.
After the chiller has been operating for approximately 30 minutes and the system has stabilized, check the operating pressures and temperatures and complete the following checks:
Note: The electronic expansion valve is commanded closed at unit shutdown and if the unit is off, there will be no refrigerant flow through the sight glasses. Only when a circuit is running will refrigerant flow be present.
The refrigerant flow through the sight glasses should be clear. Bubbles in the refrigerant indicate either low refrigerant charge or excessive pressure drop in the liquid line. A restriction in the line can sometimes be identified by a noticeable temperature differential between the two sides of the restriction. Frost may often form on the liquid line at this point. Correct refrigerant charges are shown in the General Data Tables.
Important: A clear sight glass alone does not mean that the system is properly charged. Also check the system superheat, subcooling and unit operating pressures.
Source: Trane (www.trane.com)