Daikin VRV IV RXTQ-TA / RXTQ-TB error code C1
Transmission abnormality between the indoor and fan boards
Which models this applies to. Indoor unit
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, C1 is a fault. It means transmission abnormality between the indoor and fan boards. A first thing to check: A loose, corroded or damaged connector between 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 the connector between the indoor unit PCB and the fan PCB, which is the manual instruction for C1-01, and reseat it.
What C1 means on this model
The indoor control board and the separate fan board are not communicating, so the unit has lost the ability to command or read the blower. C1-01 is the transmission fault and C1-07 is a blower motor communication error. The connector between the two boards is the first thing to check.
Symptoms you will notice
- Indoor unit shows C1 and stops
- The indoor fan does not run or runs erratically
- The unit responds to the remote controller but makes no air
- The fault appeared after the indoor unit was opened for service
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 loose, corroded or damaged connector between the indoor unit PCB and the fan PCB
- A failed fan PCB
- A wiring fault in the link between the two boards
- A failed indoor unit PCB output to the fan board
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 connector between the indoor unit PCB and the fan PCB, which is the manual instruction for C1-01, and reseat it.
- Look for corrosion or a backed-out pin, since that interface is exposed to moisture on a chilled coil.
Do not do these
- ×Do not reseat or inspect the connector with the power switch on.
- ×Do not replace the fan PCB before the connector has been checked and reseated. C1-01 names the transmission condition as the fault and the connector is the first thing to test.
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.
What it costs to fix
Parts
Fan PCB $150 to $350. Indoor unit PCB $200 to $450.
Labor
One to two hours to diagnose 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.