Daikin VRV IV RXTQ-TA / RXTQ-TB error code F6
Refrigerant overcharge
Which models this applies to. Outdoor unit
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, F6 is a fault. It means refrigerant overcharge. A first thing to check: Too much refrigerant charged into the system.
- 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
- Note whether the system started behaving differently after a service visit, since F6 on a recently serviced system usually means the charge was miscalculated.
What F6 means on this model
The system has too much refrigerant for the conditions and has shut down. Daikin lists this as its own code rather than folding it into a pressure code, which tells you it is a distinct condition. An overcharge raises head pressure and discharge temperature and can damage the compressor.
Symptoms you will notice
- Outdoor unit shows F6 and the system stops
- High discharge pipe temperature and high head pressure
- The system runs poorly in warm weather and trips on pressure codes
- The system was recently serviced and does not behave like it did before
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:
- Too much refrigerant charged into the system
- A service that topped the system up repeatedly without checking the weight
- An incorrectly sized or overfull system from installation
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.
- Note whether the system started behaving differently after a service visit, since F6 on a recently serviced system usually means the charge was miscalculated.
- Check the actual charge weight against the nameplate figure, which is the only reliable way to confirm an overcharge.
Do not do these
- ×Do not attempt to remove refrigerant without proper recovery equipment and the factory procedures.
- ×Do not assume the charge is correct because the pressures look normal at ambient. An overcharge can read plausibly until it is under load.
- ×Do not keep restarting the system on F6, since sustained high pressure and discharge temperature damage the compressor.
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 licensed technician job.
What it costs to fix
Parts
Refrigerant by the pound $40 to $120. No parts usually needed.
Labor
Two to three hours to recover, correct the charge and verify.
DIY or technician
A licensed technician job.
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.