Daikin VRV IV RXTQ-TA / RXTQ-TB error code F3
Discharge pipe temperature abnormality
Which models this applies to. Outdoor unit
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, F3 is a fault. It means discharge pipe temperature abnormality. A first thing to check: A failed discharge pipe thermistor.
- 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 the outdoor unit is rejecting heat properly, by confirming the fan is running and the coil is clean and clear.
What F3 means on this model
The discharge line sensor has read a value the control does not believe, or the discharge temperature has genuinely run outside what the compressor survives. A failed sensor and a real overheat both land here, and they have different fixes.
Symptoms you will notice
- Outdoor unit shows F3 and the system stops
- The system stops under heavy load or in hot weather
- The system stops shortly after a defrost cycle
- The discharge pipe is unusually hot or unusually cold
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 failed discharge pipe thermistor
- A refrigerant charge that is too low, which raises superheat and discharge temperature
- A compressor that is failing
- A condenser that is not rejecting heat, so head pressure and discharge temperature climb
- A non-condensing condition such as snow blocking the outdoor coil or a fan that has stopped
- A high compression ratio from a charge or metering fault
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 the outdoor unit is rejecting heat properly, by confirming the fan is running and the coil is clean and clear.
- Check for frost or snow blocking the outdoor coil in winter, since a blocked condenser raises discharge temperature sharply.
- Check the connector at the discharge thermistor.
Do not do these
- ×Do not add refrigerant to clear F3 before confirming the charge is low. A high discharge temperature is more often a condenser or airflow problem than a low charge.
- ×Do not ignore F3 and keep restarting the system. Sustained high discharge temperature destroys compressor windings.
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. Checking that the outdoor fan runs and the coil is clear is a reasonable homeowner step.
What it costs to fix
Parts
Discharge thermistor $30 to $90. Compressor $1,400 to $3,000 if the compressor has been damaged.
Labor
Two to four hours depending on cause.
DIY or technician
A technician job. Checking that the outdoor fan runs and the coil is clear is a reasonable homeowner step.
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.