Daikin VRV
Faulty Daikin Compressors
Case Study


The customer commissioned a Daikin VRV Heat Recovery System, and the HVAC worked for ~2 years. 

The customer was satisfied with the HVAC.

Customer challenge

After ~2 years both of the inverter compressors were faulty; a rare case where both are. 

The Customer decided to switch the service company for the replacement. The compressors were replaced and activated, but the root cause was still unknown.

The Traditional Course of Action
Schedule a site visit
Travel to site
Connect a service tool, and collect a current, limited operational data
Analyze the collected data
Find the fault and fix it
Collect new data and verify the fix
Remote Service Course of Action

The service team performed a checkup, using CoolMasterNet and CoolAutomation’s HVAC Remote Diagnostics solution – and found irregular readings.

When both inverter compressors units were heating – both were heating just fine. But when one unit was in Heat mode and the other was Off – the unit in Heat mode was actually cooling.

By using the HVAC Remote Diagnostics solution, the VRF expert gained remote access to the site’s data. Based on the data, he suspected a swap of control lines between the two units (in this case: AV and Bedroom 1).

A team of junior service providers was sent to the site. Upon arrival at the site they opened the ceiling, and indeed – the control lines were swapped between the units.

After fixing the issue technically, the team used the HVAC Remote Diagnostics solution again. They repeated the operational sequence and saw that now, both units were working correctly.

And so, the root cause was reaffirmed: the control swap was probably the major factor in the compressor(s)’ fault, and liquid refrigerant may have entered the suction pipe.

Access the system remotely from the comfort of the office to test the system and find fault
AV Room & Bed1 have crossed F1-F2 BS-indoor cables
Send a Junior VRF Engineer for 1 hour On-Site to perform the fix
Verify the fix remotely
After correcting the cross cables, Bed 1 is in Heat mode (although AV Rack unit is off)


Traditional HVAC Service
Remote HVAC Service
On-site long data recording with the essential need for the error to re-emerge (will not appear if both units are operating)
Offsite remote system test and fault finding
Multiple trips to the site are expected
Less than 1 hour of on-site junior VRF service provider
Analysis of the raw data gathered with minimal assistance from the tool, involving a Senior VRF expert on-site for a considerable amount of time
Remote fix verification
On-site fix
On-site verification test


Minimal customer disturbance
Only one trip, versus multiple trips
Simplified data analysis

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