Carrier AquaSnap 30MPA Series Controls, Start-up, Operation, Service, And Troubleshooting

Also see for AQUASNAP 30MPA: User manual Operation and service manual Installation instructions

Carrier AquaSnap 30MPA Series Controls, Start-up, Operation, Service, And Troubleshooting Manual pdf 53 page image

53Table 51 — TroubleshootingCHILLED 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 scrollingmarquee.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 iscomplete.COOLING LOAD SATISFIED — Unit shuts down whencooling load has been satisfied. Unit restarts when required tosatisfy leaving fluid temperature set point.THERMISTOR FAILURE — If a thermistor fails in either anopen or shorted condition, the unit will be shut down. ReplaceEWT, or LWT as required. Unit restarts automatically, but mustbe reset manually by resetting the alarm with the scrollingmarquee.ENABLING AND DISABLING COMPRESSORS —Compressors in the 30MP units can be enabled or disabled inthe controls. To enable or disable a compressor, toggle thevalue in the ConfigurationSERV menu for each individualcompressor.COMPRESSOR DISCHARGE CHECK VALVE — Adisk-type check valve in the discharge of the compressor pre-vents high pressure discharge gas from flowing rapidly backthrough the compressor at shutdown. This same check valveprevents a high to low side bypass in multiple compressorcircuits.LOW SATURATED SUCTION — Several conditions canlead to low saturated suction alarms and the chiller controlshave several override modes built in which will attempt to keepthe chiller from shutting down. Low fluid flow, low refrigerantcharge and plugged filter driers are the main causes for thiscondition. To avoid permanent damage and potential freezingof the system, do NOT repeatedly reset these alert and/or alarmconditions without identifying and correcting the cause(s).COMPRESSOR SAFETIES — The 30MP units with Com-fortLink controls include a compressor protection board thatprotects the operation of each of the compressors. Each boardsenses the presence or absence of current to each compressor.SYMPTOMS CAUSE REMEDYCompressor CyclesOff on Loss of ChargeLoss of charge control. Acting erratically. Repair leak and recharge.Replace control.Low refrigerant charge Add refrigerant.Low suction temperature Raise cooler leaving fluid temperature set point.Compressor Cycles Off on Outof Range ConditionThermistor failure Replace thermistor.System load was reduced faster than controller couldremove stagesUnit will restart after fluid temperature rises back into thecontrol band. Avoid rapidly removing system load orincrease loop volume.Temperature controller deadband setting is too low Raise deadband setting.Compressor Shuts Down onHigh-Pressure ControlHigh-pressure control acting erratically Replace control.Noncondensables in system Purge system.Condenser scaled/dirty (30MPW) Clean condenser.Fans in remote condensing unit (30MPA only) not operating Repair or replace if defective.System overcharged with refrigerant Reduce charge.Unit Operates Too Longor ContinuouslyLow refrigerant charge Add refrigerant.Control contacts fused Replace control.Air in system Purge system.Partially plugged or plugged expansion valve or filter drier Clean or replace as needed.Defective insulation Replace or repair as needed.Service load Keep doors and windows closed.Damaged compressor Check compressor and replace if necessary.Unusual or Loud SystemNoisesPiping vibration Support piping as required.Check for loose pipe connections or damaged compressorExpansion valve hissing Check refrigerant charge.Check for plugged liquid line filter drier.Compressor noisy Replace compressor (worn bearings).Check for loose compressor holddown bolts.Operation outside of compressor operating envelope. Con-sider head pressure control, clean condenser. Check waterflow (cooler and condenser).Compressor not pumping Advanced scroll temperature protection is active. Determinehigh discharge temperature reason.Compressor Loses Oil Leak in system Repair leak.Mechanical damage (Failed seals or broken scrolls) Replace compressor.Oil trapped in line Check piping for oil traps.Hot Liquid Line Shortage of refrigerant due to leak Repair leak and recharge.Frosted Liquid Line Restricted filter drier Replace filter drier.Frosted Suction Line Expansion valve admitting excess refrigerant (note: this is anormal condition for brine applications) Replace valve if defective.Stuck TXV (thermostatic expansion valve) Replace valve if defective.Freeze-Up Improper charging Make sure a full quantity of fluid is flowing through the coolerwhile charging, and suction pressure in cooler is equal to orgreater than pressure corresponding to 32 F (0° C).System not drained for winter shutdown Recommended that system be filled with an appropriate gly-col mixture to prevent freezing of pumps and fluid tubing.Loose thermistor Verify thermistors are fully inserted in wells.CAUTIONIf unit stoppage occurs more than once as a result of any ofthe safety devices listed, determine and correct causebefore attempting another restart.