•Check condenser coils for debris, clean as necessary.
Every month:
•Check moisture indicating sight glass for possible refrig- erant loss and presence of moisture.
Every 3 months (for all machines):
•Check refrigerant charge.
•Check all refrigerant joints and valves for refrigerant leaks, repair as necessary.
•Check chilled water flow switch operation.
•Check all condenser fans for proper operation.
•Check compressor oil level.
Every 12 months (for all machines):
•Check all electrical connections, tighten as necessary.
•Inspect all contactors and relays, replace as necessary.
•Check accuracy of thermistors, replace if greater than
± 2° F (1.2° C) variance from calibrated thermometer.
•Obtain and test an oil sample. Change oil only if necessary.
•Check to be sure that the proper concentration of anti- freeze is present in the chilled water loop, if applicable.
•Verify that the chilled water loop is properly treated.
•Check refrigerant filter driers for excessive pressure drop, replace as necessary.
•Check chilled water strainers, clean as necessary.
•Check cooler heater operation, if equipped.
•Check condition of condenser fan blades and that they are securely fastened to the motor shaft.
•Perform Service Test to confirm operation of all components.
•Check for excessive cooler approach (Leaving Chilled Water Temperature — Saturated Suction Temperature) which may indicate fouling. Clean cooler vessel if necessary.
Microchannel Heat Exchanger (MCHX) Con- denser Coil Maintenance and Cleaning Recommendations
CAUTION
Do not apply any chemical cleaners to MCHX condenser coils. These cleaners can accelerate corrosion and damage the coil.
Routine cleaning of coil surfaces is essential to maintain proper operation of the unit. Elimination of contamination and removal of harmful residues will greatly increase the life of the coil and extend the life of the unit. The following steps should be taken to clean MCHX condenser coils:
1.Remove any foreign objects or debris attached to the coreface or trapped within the mounting frame and brackets.
2.Put on personal protective equipment including safety glasses and/or face shield, waterproof clothing and gloves. It is recommended to use full coverage clothing.
3.Start high pressure water sprayer and purge any soap or industrial cleaners from sprayer before cleaning condens- er coils. Only clean, potable water is authorized for clean- ing condenser coils.
4.Clean condenser face by spraying the core steady and uniformly from top to bottom while directing the spray straight toward the core. Do not exceed 900 psig or 30 de- gree angle. The nozzle must be at least 12 in. from the
core face. Reduce pressure and use caution to prevent damage to air centers.
CAUTION
Excessive water pressure will fracture the braze between air centers and refrigerant tubes.
TROUBLESHOOTING
Complete Unit Stoppage and Restart — Possi- ble causes for unit stoppage and reset methods are shown be- low and in Table 41. Refer to Fig. 3-7 for component arrange- ment and control wiring diagrams.
GENERAL POWER FAILURE — After power is restored, restart is automatic through normal MBB start-up.
UNIT ENABLE-OFF-REMOTE CONTACT SWITCH IS OFF — When the switch is OFF, the unit will stop immediate- ly. Place the switch in the ENABLE position for local switch control or in the REMOTE CONTACT position for control through remote contact closure.
CHILLED FLUID PROOF-OF-FLOW SWITCH OPEN — After the problem causing the loss of flow has been corrected, reset is manual by resetting the alarm with the scrolling mar- quee as shown in Table 42.
OPEN 24-V CONTROL CIRCUIT BREAKER(S) — De- termine the cause of the failure and correct. Reset circuit break- er(s). Restart is automatic after MBB start-up cycle is complete.
COOLING LOAD SATISFIED — Unit shuts down when cooling load has been satisfied. Unit restarts when required to satisfy leaving fluid temperature set point.
THERMISTOR FAILURE — If a thermistor fails in either an open or shorted condition, the unit will be shut down. Replace EWT, LWT, or OAT as required. Unit restarts automatically, but must be reset manually by resetting the alarm with the scrolling marquee as shown in Table 42.
CAUTION
If unit stoppage occurs more than once as a result of any of the safety devices listed, determine and correct cause before attempting another restart.
LOW SATURATED SUCTION — Several conditions can lead to low saturated suction alarms and the chiller controls have several override modes built in which will attempt to keep the chiller from shutting down. Low fluid flow, low refrigerant charge and plugged filter driers are the main causes for this condition. To avoid permanent damage and potential freezing of the system, do NOT repeatedly reset these alert and/or alarm conditions without identifying and correcting the cause(s).
COMPRESSOR SAFETIES — The 30RAP units with Com- fortLink™ controls include a compressor protection board that protects the operation of each of the compressors. Each board senses the presence or absence of current to each compressor.
If there is a command for a compressor to run and there is no current, then one of the following safeties or conditions have turned the compressor off:
Compressor Overcurrent — All compressors have internal line breaks or a motor protection device located in the com- pressor electrical box.
Compressor Short Circuit — There will not be current if the compressor circuit breaker that provides short circuit protection has tripped.
Compressor Motor Over Temperature — The internal line- break or over temperature switch has opened.
