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The latest industry insights from the pros at AirReps.
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VRV System Not Communicating? Here’s What We Check First
Whether the system is missing indoor units, throwing U4 alarms, or not seeing devices correctly, the issue is usually related to communication wiring, addressing, or controller setup. Before getting too deep into troubleshooting, we typically start by verifying the communication path and indoor unit count. Here are a few of the first things we typically check in the field. Common Symptoms U4 communication alarms  Missing indoor units during startup  Group addresses not appearing  Fan...
Connor Sawyer
May 18, 2026
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Daikin VRV
VRV System Not Communicating? Here’s What We Check First
Whether the system is missing indoor units, throwing U4 alarms, or not seeing devices correctly, the issue is usually related to communication wiring, addressing, or controller setup. Before getting too deep into troubleshooting, we typically start by verifying the communication...
Daikin VRV
Understanding the U4 Error Code in Daikin VRV Systems
Understanding the U4 Error Code in Daikin VRV Systems If you’re seeing a U4 error code on your Daikin Variable Refrigerant Volume (VRV) system, you’re dealing with a communication issue that needs prompt attention. This error is one of the most common diagnostic codes...
Daikin VRV
Daikin VRV, A2L requirements, 2021 IMC, and ASHRAE 15
Our team of HVAC experts at AirReps has now been through several Daikin VRV projects across Washington under A2L requirements, and the process is starting to become more consistent. The code framework itself, including the 2021 IMC and ASHRAE 15, is well established. What has taken...
Velo
Stabilizing Performance and Reducing Swing Tank demand with the new generation of Domestic HWHPs
As the era of decarbonization brings focus to the domestic hot water production of buildings, heat pumps have become the leading technology utilized to achieve this goal with great success. Fossil fuels can be removed from systems and high COPs can be achieved, even as...
ONICON Insertion Turbine Meter
ONICON Insertion Turbine Meter Diagnostics
Here at AirReps, our team of HVACR experts hears it all! We’re always answering questions about HVACR systems that are facing issues in running properly. Every so often we get a call from a customer wondering why their turbine meter...
BACnet, VFDs
Ways to Program a Run Status for the VFD on an HVAC System
The entire team here at AirReps, which now includes the Control Products Group division, is dedicated to helping customers and partners with all of their HVAC needs, 24/7. That’s why when we had a customer reach out with an issue on their HVAC...
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