Daikin VRV IV RXTQ-TA / RXTQ-TB error code C6
Indoor unit and fan board combination error
Which models this applies to. Indoor unit
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, C6 is a fault. It means indoor unit and fan board combination error. A first thing to check: A defective combination of the indoor unit PCB and the fan PCB.
- 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
- Check whether the capacity setting adaptor is correct and whether the type of fan PCB is correct, because that is the manual instruction for C6-01 and it covers two of the three conditions under this code.
What C6 means on this model
A compatibility code rather than a failure. C6-01 covers a defective combination of the two boards, a blower motor HP mismatch, an incorrect capacity setting adaptor and an incorrect fan board type, and C6-02 covers an indoor blower that lacks the required parameters.
Symptoms you will notice
- Indoor unit shows C6 and stops
- The fan does not run even though the unit responds
- The fault appeared after a board was replaced
- A capacity setting adaptor is missing or wrong
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:
- A defective combination of the indoor unit PCB and the fan PCB
- A blower motor HP mismatch between the fan board and the motor
- An incorrect capacity setting adaptor
- An incorrect type of fan PCB fitted
- An indoor blower that lacks the parameters required to function
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.
- Check whether the capacity setting adaptor is correct and whether the type of fan PCB is correct, because that is the manual instruction for C6-01 and it covers two of the three conditions under this code.
- Confirm the fan PCB fitted is the part specified for this indoor unit model, and that it was not carried over from a different unit.
Do not do these
- ×Do not swap a fan PCB between similar-looking indoor units to clear this code. The mismatch is exactly what the code is reporting, and the motor HP has to match the board.
- ×Do not change the capacity setting to make a mismatched board pass. That moves the fault into system metering rather than fixing 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 technician job. Part numbers and the capacity setting adaptor have to be matched to the model.
What it costs to fix
Parts
Fan PCB $150 to $350 if the wrong one was fitted. Capacity setting adaptor $20 to $80.
Labor
One to two hours to identify and correct the mismatch.
DIY or technician
A technician job. Part numbers and the capacity setting adaptor have to be matched to the model.
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
- Models in scope
- Daikin VRV IV RXTQ-TA / RXTQ-TB
- 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.