Daikin VRV IV RXTQ-TA / RXTQ-TB error code J7
Outdoor heat exchanger liquid pipe thermistor abnormality, R7T
Which models this applies to. Outdoor unit
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, J7 is a fault. It means outdoor heat exchanger liquid pipe thermistor abnormality, r7t. A first thing to check: A failed R7T thermistor.
- Applies to
- Daikin VRV IV RXTQ-TA / RXTQ-TB
- Daikin VRV IV RXTQ heat pump codes · Heat Pump
- Type of code
- Fault
- Urgency: Book a technician
- First safe check
- Confirm R7T is clipped to the liquid line and that the wire is undamaged.
What J7 means on this model
The R7T thermistor on the liquid line leaving the outdoor coil has reported a fault. The control uses it to track what the coil is condensing, so it will not run on an unmeasurable liquid line temperature.
Symptoms you will notice
- Outdoor unit shows J7 and the system stops
- The system will not start
- The system will not hold capacity
- The fault followed work on the outdoor unit
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 R7T thermistor
- A loose or broken wire at the thermistor
- A disturbed connector
- A clip that has come loose off the liquid line
- A thermistor whose resistance is out of range
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.
- Confirm R7T is clipped to the liquid line and that the wire is undamaged.
- Check the connector at the sensor.
- Compare the resistance against the pipe temperature using the resistance chart in the manual.
Do not do these
- ×Do not work on the connector with the power switch on.
- ×Do not route the sensor wire across a hot line where it will be chafed.
When to call a technician
Worth scheduling, and worth your own checks first
You can usually keep living with this for a short while, but it will not fix itself. Do the safe checks below first, because a tripped switch or a blocked airflow is a five-minute fix that would otherwise cost you a service call.
- 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.
What it costs to fix
Parts
Liquid line thermistor $30 to $90.
Labor
One to two hours to test and replace.
DIY or technician
A 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.