All UNICOOL models come with variable speed compressor and inverter/variable frequency drive. It is essential to record and identify the alarm code with error information when troubleshooting inverter related issues and alarms. This article provides a troubleshooting guide for the inverter issues on UNICOOL models.



Access Inverter Alarm

*Inverter alarms can be viewed from the display on software revision 2.1.024 and newer revision. If your equipment have older software version, please use the link below to download the updated revision: ASMUC Software Download.

Software Upgrade instruction can be found through the link: ASMUC Software Upgrade Instructions


  • On WPU/HVAC unit, inverter alarm can be found under default display--> Information-->4th page down





Interpret Alarm Code

There are 16 digits for each alarm code. Each digit represent one of the alarms. The inverter alarms use only the characters "1" and "0". On each digit, "1" stands for active alarm and "0" stands for no active alarm. 



Let's look at an example with one active inverter alarm:

There is "1" on digit 6 under Alarm Code 1. By looking at troubleshooting guide, it represents High Voltage Alarm on Power Supply. 



Troubleshooting Inverter Alarm


Digit


Error InformationPossible CauseRecommended Action
Alarm Code 1
1Compressor/Shorted Inverter Output1. Compressor damage      
2. Shorted electrical circuit
3. Site load over system capacity
4. Wiring issue between inverter and compressor		1. Replace compressor        
2. Replace inverter
3. Verify site load vs system capacity
4. Correct/tighten wiring according to the wiring diagram 
2

Compressor Error1. Compressor damage        
2. Compressor operate in wrong direction
3. Site load over system capacity
4. Wiring issue between inverter and compressor		1. Replace compressor          
2. Replace inverter
3. Verify site load vs system capacity
4. Correct/tighten wiring according to the wiring diagram 
3Circuit Temperature Transducer1. Circuit temp transducer error1. Replace inverter
4Electric Circuit Overheating1. Heat dissipation is poor1. Verify air flow around the inverter and clean heat sink
2. Verify the radiator fan operation if applied
5Power Supply Low Voltage1. Low voltage input            
2. Incorrect input wiring
3. Inverter damage		1. Check input voltage        
2. Correct/tighten wiring according to the wiring diagram
3. Replace inverter 
6Power Supply High Voltage1. High voltage input              
2. Incorrect input wiring
3. Inverter damage		1. Check input voltage      
2. Correct/tighten wiring according to the wiring diagram
3. Replace inverter 
7Output Phase Lost1. Incorrect wiring between inverter and compressor      
2. Inverter damage
3. Compressor damage		1. Correct/tighten wiring according to the wiring diagram
2. Replace inverter
3. Replace compressor
8Power Supply Input Phase Lost1. Power supply wiring error1. Correct/tighten wiring according to the wiring diagram  
9Software Overload1. Compressor damage      
2. Shorted electrical circuit
3. Site load over system capacity
4. Wiring issue between inverter and compressor		1. Replace compressor
2. Replace inverter
3. Verify site load vs system capacity
4.  Correct/tighten wiring according to the wiring diagram 
10Communication Error1. Incorrect wiring on the communication cable
2. No connection between inverter and control board		1. Verify the communication wiring (RS485+, RS485-) in correct polarity
2. Replace inverter
12Low Voltage Alarm1. Low voltage input          
2. Incorrect input wiring
3. Inverter damage		1. Check input voltage        
2. Correct/tighten wiring according to the wiring diagram
3. Replace inverter 
13High Voltage Alarm1. High voltage input          
2. Incorrect input wiring
3. Inverter damage		1. Check input voltage          
2. Correct/tighten wiring according to the wiring diagram
3. Replace inverter 
15EEPROM Error1. Inverter damage1. Replace inverter
16Inverter Communication Circuit Board Error1. Circuit board damage1. Replace inverter
Alarm Code 2
1System Shutdown Due to Overheat1. Environment overheat1. Verify air flow around the inverter and clean heat sink
2. Verify the radiator fan operation if applied
2, 3Environment Temperature Transducer Error1. Transducer damage1. Replace inverter
4Electrical Circuit Board Failure1. Circuit board damage1. Replace inverter
5Inverter Radiator Fan Error1. Fan blade stuck
2. Inverter fan damage		1. Remove obstruction and clean the fan blade
2. Replace the radiator fan
Alarm Code 3
1EEPROM Error1. Inverter damage
1. Replace inverter
2Rapid Decrease Frequency Due to Overheat
1. Hardware overheat1. Verify air flow around the inverter and clean heat sink
2. Verify the radiator fan operation if applied
3Slowly Decrease Frequency Due to Overheat1. Hardware overheat1. Verify air flow around the inverter and clean heat sink
2. Verify the radiator fan operation if applied
4Frequency Limited Due to Overheat1. Hardware overheat
1. Verify air flow around the inverter and clean heat sink
2. Verify the radiator fan operation if applied
6
Software Overload1. Compressor damage
2. Shorted electrical circuit
3. Site load over system capacity
4. Wiring issue between inverter and compressor
1. Replace compressor
2. Replace inverter
3. Verify site load vs system capacity
4.  Correct/tighten wiring according to the wiring diagram
7
Communication Error
1. Incorrect wiring on the communication cable
2. No connection between inverter and control board
1. Verify the communication wiring (RS485+, RS485-) in correct polarity
2. Replace inverter
8System Overheat1. Environment overheat
1. Verify air flow around the inverter and clean heat sink
2. Verify the radiator fan operation if applied
9Radiator Fan Error1. Fan wiring error
2. Radiator fan damage
1. Correct/tighten wiring according to the wiring diagram
2. Replace radiator fan
10Temperature Transducer Error
1. Transducer damage
1. Replace inverter