Carrier 48FK Controls Operation And Troubleshooting

Carrier 48FK Controls Operation And Troubleshooting Manual pdf 44 page image

TROUBLESHOOTINGBy using the display module, actual operating conditionsof the unit are displayed while it is running. The Quick Testfunction allows proper operation of compressors, compres-sor unloaders, fans, and other components to be checked whileunit is stopped. If an operating fault is detected, an alarm isgenerated and an alarm code(s) is displayed. For checkingspecific items, see Table 20.Checking Display Codes — To view the digital dis-play codes, press the button located to the right of the LEDdisplay/set point board in the control box. See Table 21 forOperational Status Codes. See Table 22 for Diagnostic Codes.Complete Unit Stoppage — If the unit is off, thereare several conditions that can cause this situation to occur:• Remote ON/OFF circuit in Unoccupied mode.• Unit ON/OFF switch moved to OFF position.• Programmed schedule at the timeclock.• General power failure.• Blown fuse in the control power feed.• Open control circuit fuse.• Operation of the unit blocked by the demand limitfunction.• Unit supply-air temperature (T1) thermistor failure.• Supply-air fan is not operating.• High duct static pressure.Single Circuit Stoppage — If a single circuit stops,there are several potential causes:• Open contacts in the compressor high-pressure switch.• Low refrigerant pressure.• Thermistor failure.• Unit supply-air temperature thermistor (T1) failure.• Compressor circuit breaker trip.• Operation of the circuit blocked by the demand limitfunction.Table 21 — Operation Status CodesCODE MEANING□0 0 cooling stages active□1 1 cooling stage active□2 2 cooling stages active□3 3 cooling stages active□4 4 cooling stages active□5 5 cooling stages active□6 6 cooling stages active□7 7 cooling stages active□8 8 cooling stages active□20Initialization mode (Allow 2 minutesfor initialization. To initiate Quick Test,press the Display button while 20 is displayed.)□21 Temperature Reset in effect□22 Demand Limit in effect□26 Morning Warm-Up in effect□30 Internal failure detected□88 Self-diagnostic mode in effectRestart Procedure — Before attempting to restart themachine, check the display for alarm codes to determine thecause of the shutdown. If the unit, circuit, or compressor stopsmore than once as a result of a safety device, determine andcorrect the cause before attempting to start the unit again.After the cause of the shutdown has been corrected, unitrestart may be automatic or manual depending upon the fault.Table 20 — Controls TroubleshootingSYMPTOM(S) PROBABLE CAUSE(S) SOLUTION(S)Controls do not seemto be operating. Remote on-off function may bekeeping controls off. Check status.Evaporator fan does not run. 1. Circuit breaker open.2. Inverter overload (if equipped). 1. Find cause and reset circuit breaker.2. Find cause and reset.Compressor does not run. 1. Circuit breaker is open.2. There is no demand for cooling.3. The control is locking out cooling operation.4. Demand Limit in effect.1. Find cause and reset circuit breaker.2. Correct operation.3. Check rotating display for alarm codes. Resolvealarm cause and reset control by changing tostandby and back to run mode.4. Check Demand Limit Settings.Condenser fans do notturn on. Circuit breaker is open. Find cause and reset circuit breakerCooling demand exists andeconomizer modulates, butcompression is not operating.Compression cannot be initiateduntil economizer damper is 90% open. Correct operation.44