Carrier Infinity 24VNA6 Series Service Manual

Also see for Infinity 24VNA6: Installation instructions Owner's manual

24VNA6 / 25VNA4: Service ManualManufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.18Code 25-24 Model Plug ChangedCode 25-24 indicates that the model plug presently installed is differentfrom the previously stored valid model plug value. Code 25-24 will beset when the equipment is powered up with a valid model plug value thatis different from the stored model plug value in memory. A changedmodel plug will affect control configuration only if that model plug waspresent when power was applied to the equipment. Code 25-24 will beset if the model plug is changed to a different valid value or an invalidvalue while power is applied to the unit. If the model plug change isintentional, then no corrective action is required. Leave the new modelplug in place and the code will clear on its own when power is removedand reapplied to the equipment. If the model plug change is notintentional, then remove power from the equipment, install the correctmodel plug, and reapply power to the equipment.Code 25-61 Invalid Model Plug LockoutEach system requires a model plug to be installed on the PCM. Themodel plug consists of two resistors in a unique combination. Thismodel plug identifies the system size and type so PCM software canapply the relevant operating limits and reference correct operatingtables. Code 25-61 designates the currently installed model plug is notvalid and does not match any possible model in variable speed software.Consult unit installation instructions for model plug to unit model crossreference and replace model plug with correct part. While Code 25-61 isactive, the unit will not be operable.Code 25-63 VFD System Lockout - Model MismatchThis code is generated when the sensed physical model plug isrecognized but not compatible with the installed VFD. Check installedmodel plug against table in installation instructions for the model beingserviced. Replace with correct VFD or model plug part.Code 26-26 PCM MCU Old Version AThis fault is set when the PCM microcontroller on installed board isrecognized as old. This board should not be used in the field and shouldbe returned to Carrier for warranty replacement.Code 26-27 PCM Reprogramming FailureCode 26-27 indicates that an attempt for the PCM to reprogram itselffailed. If this diagnostic is not recent, then a subsequent reprogrammingattempt may have succeeded. The technician should check the currentPCM software version against the latest software release. If the PCMsoftware is not the most current, then the PCM should be reprogrammedmanually using the Infinity Control or the Carrier Service Tech App.Code 26-31 External EEPROM Write FailureThe PCM stores equipment configuration information in non-volatileEEPROM memory. An active Code 26-31 can be corrected only byreplacing the PCM.Code 28-71 Fuse 1 Open LockoutThis code will be set if fuse 1 is blown or missing on PCM board. Fuse 1powers PEV, RVS, and Bluetooth module. When fuse 1 is open none ofthese components will function. AC units will operate if pressuredifferential is below the maximum allowable starting threshold (100psi),but HP units will not operate at all. The code will clear once short isremoved and fuse is replaced with new, undamaged part. If fuse is blownthere is a likely short in either the PEV, RVS, or Bluetooth moduleharnesses. If no physical damage is observed, begin by unplugging allcomponents from PCM and make connections until replacement fuseopens. Harness should be repaired before replacing fuse. See wiringdiagram for fuse size and locationCode 28-72 Fuse 2 Open LockoutThis code will be set if fuse 2 is blown or missing on PCM board. Fuse 2only powers the LLS. When this fault is active the system will notoperate. The code will clear once fuse is replaced with new, undamagedpart. LLS are field installed accessories. Check LLS wiring for shorts.See wiring diagram for fuse size and location.Code 31-11 Compressor High Pressure LimitingCode 31-58 Compressor High Pressure LockoutThis system contains a discharge pressure transducer to ensurecompressor reliability. The high pressure limit is based on compressormodel and varies with operating speed. When this fault occurs, thesystem will shut down and restart after 5 minute compressor protectiontime delay if demand is still present. Each time the fault occurs themaximum allowable compressor speed will be reduced by 25% until theminimum allowable compressor speed is reached. Each hour ofcompressor operation without fault re-occurrence will increase thecompressor speed limit by 25%. This ensures that partial operation isstill possible and system will self-correct if the issue causing fault isremoved. Code 31-58 occurs when the compressor high pressure limit isreached while the compressor is at its minimum operating speed. Systemwill "lock out" for 2 hours and attempt to resume normal operationafterwards. Multiple external factors may generate this fault: Dirtycondenser, lack of airflow across condenser, condenser airflowrecirculation, extreme high temperature and sun loading, refrigerantcircuit blockage, faulty EXV/TXV, or overcharge.Code 31-16 High Pressure Switch ShutdownThis system contains a 670psi high pressure switch as well as adischarge pressure transducer. This fault should not occur as the pressuretransducer utilizes a separate high pressure limit at a lower setting. In thecase of a fast transient this switch will safely disable system operation.This switch is connected directly to VFD and a break or short in wireharness during high pressure events will also generate fault. The highpressure switch quickly shuts down high voltage to VFD and additionalcommunication faults may occur since the VFD will cease tocommunicate with PCM. The PCM/VFD will not attempt to resumesystem operation until discharge pressure has dropped below 425PSIG.Ensure HPS is closed and securely connected to VFD.Code 31-19 High Pressure DisableThis fault is triggered when the discharge pressure is too high to startcompressor (620psig). If refrigerant saturated pressure is high enoughthe system will be inoperable until pressures drop to acceptable range.Extreme high ambient temperatures may cause this fault to set andsystem will be inoperable during this time.Code 32-15 Compressor Low Suction ShutdownCode 32-55 Compressor Low Suction LockoutExceeding soft and hard low pressure limits result in code 32-15. Thesoft low pressure limit can be exceeded for up to 2 minutes before codeis generated, while exceeding the hard limit immediately results in code32-15. Low pressure limits are compressor and rpm dependent, but 30psiand 15psi are typical. 4 occurrences of code 32-15 result in a 2hourlockout. Note: AEM will attempt to mitigate low pressure by adjustingsystem operation. This fault will only be set if system operation cannotbe modified quickly enough to prevent exceeding hard and soft limits. Asingle occurrence of fault will result in 5 minute time delay followed byattempted restart if demand is still present.Low pressure conditions can occur from multiple causes: Blockage inliquid line, stuck TXV or EXV, no airflow across evaporator, low systemcharge. Low ambient temperatures will increase diagnostic sensitivity tocontributing factors above. Check pressure drop of liquid line atcondenser and evaporator, confirm airflow across evaporator, andconfirm system charge is correct. Replace EXV/TXV if necessary.Code 32-59 Low Pressure LockoutThis fault is triggered when the suction pressure is too low to safely startthe compressor. If refrigerant saturated pressure is low enough thesystem will be inoperable until pressures increase to acceptable range.System will be inoperable while this fault is active. The most likelycause of this fault is a leak in the refrigeration system.