Daikin VRV IV RXTQ-TA / RXTQ-TB error code UA
Improper indoor and outdoor unit combination
Which models this applies to. System
What is specific to the VRV IV RXTQ-TA / RXTQ-TB platform
The RXTQ outdoor unit serves VRV indoor units over a shared communication bus, and the factory splits the code list by which unit reports it. A and C codes come from indoor units, E, F, H, J, L and P from the outdoor unit, and U and M are system or centralized controller faults. This is a commercial and light commercial multi split platform, not a residential one indoor mini split unit.
Your control board prints the code as text, for example F01 or EE3, so you read it off the display rather than counting blinks. The printed number is the fault itself, not a position in a table.
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, UA is a fault. It means improper indoor and outdoor unit combination. A first thing to check: More indoor units connected than the outdoor unit can serve.
- Applies to
- Daikin VRV IV RXTQ-TA / RXTQ-TB
- Daikin VRV IV RXTQ heat pump codes · Heat Pump
- Type of code
- Fault
- Urgency: Needs attention soon
- First safe check
- Count the connected indoor units and compare their total capacity against the outdoor unit rating and the connectable indoor unit ratio in the manual.
What UA means on this model
The combination of indoor units connected to this outdoor unit is not one the system can run, or an electric heater capacity setting does not match the equipment. A system outside the connectable indoor unit ratio or capacity range reports this rather than attempting to run.
Symptoms you will notice
- Outdoor unit shows UA and the system will not start
- The system is newly installed or has had an indoor unit added
- The system ran before an indoor unit was changed or added
- The system is at or beyond its connectable indoor unit capacity
Common causes
The code tells you what the control detected, not which part failed. These are the causes we see most often, roughly in order of likelihood:
- More indoor units connected than the outdoor unit can serve
- Fewer indoor units connected than the outdoor unit requires
- Indoor units outside the compatible range for the outdoor unit
- An incorrect electric heater capacity setting
- An indoor unit swapped for a different model without reconfiguring
- Field settings that do not match the equipment installed
What you can safely check
These are homeowner-level checks. None of them need you to open a live electrical compartment or work on gas.
- Count the connected indoor units and compare their total capacity against the outdoor unit rating and the connectable indoor unit ratio in the manual.
- Check whether the system is new or has had an indoor unit added or swapped recently, because that is when this code appears.
- Check the electric heater capacity setting against any heater actually fitted.
Do not do these
- ×Do not force the system to run on an out of range combination. The outdoor unit sizes its refrigerant control to the connected load.
- ×Do not change the electric heater capacity setting to make the code clear without the design data, because the setting affects how the unit meters heat.
- ×Do not split a system across two outdoor units to work around this without a proper design, since refrigerant balance across the whole system depends on it.
When to call a technician
Book a technician, do not keep resetting it
This fault will not clear on its own. Every power cycle gives the control one more failed attempt, and repeated attempts are what turn a cheap part replacement into a seized or contaminated system.
- The refrigerant circuit is sealed and legally requires licensed handling. Opening it without certification releases refrigerant and can put the whole system in violation of regulation, so a low-pressure or high-pressure fault on this equipment is a call-out, not a weekend job.
- If the appliance has stopped mid-cycle, is making a noise you have not heard before, or smells burnt, stop reading here and call. Those are symptoms of something the fault code does not describe well enough.
A design and commissioning technician job. The manual contains the compatibility and ratio tables and they are the deciding factor.
What it costs to fix
Parts
None expected. This is a configuration error.
Labor
Two to four hours to redesign the combination or correct the settings.
DIY or technician
A design and commissioning technician job. The manual contains the compatibility and ratio tables and they are the deciding factor.
Typical US part and labor ranges, 2026. They vary by region, model and contractor, so treat them as a planning figure, not a quote.
Scope of this code
- Code table
- Daikin VRV IV RXTQ heat pump codes
- How this model reports the code
- Printed on the control display
- Models in scope
- Daikin VRV IV RXTQ-TA / RXTQ-TB
- How this platform differs
- The RXTQ outdoor unit serves VRV indoor units over a shared communication bus, and the factory splits the code list by which unit reports it. A and C codes come from indoor units, E, F, H, J, L and P from the outdoor unit, and U and M are system or centralized controller faults. This is a commercial and light commercial multi split platform, not a residential one indoor mini split unit.
- Checked
- Confirm on your own unit
- Find the model number on the data plate, then check this code in the service manual for that model. Manufacturers revise code tables between model years, and a revised board can renumber a fault.