Daikin VRV IV RXTQ-TA / RXTQ-TB error code AF
Drain water level above the limit, warning
Which models this applies to. Indoor unit
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, AF is a fault. It means drain water level above the limit, warning. A first thing to check: A blocked or slow condensate drain.
- Applies to
- Daikin VRV IV RXTQ-TA / RXTQ-TB
- Daikin VRV IV RXTQ heat pump codes · Heat Pump
- Type of code
- Fault
- Urgency: Worth keeping an eye on
- First safe check
- Check the drain line is falling continuously all the way to its point of discharge, because a section that runs flat will hold water back even when the pipe is clear.
What AF means on this model
Condensate has risen above the level the unit will accept and the fan has stopped. The operation lamp stays lit, so this is a warning rather than a stop, but the water is real and it is the same drain circuit that produces A3.
Symptoms you will notice
- Indoor unit shows AF with the operation lamp lit
- Water dripping below the indoor unit
- The fan stops and the unit will not cool
- A drain that has been slow to clear 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:
- A blocked or slow condensate drain
- A drain pump that is slow or has lost prime
- A pan that has not been cleaned and has filled with biofilm
- A drain line that has been pushed up or is draining uphill somewhere
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 drain line is falling continuously all the way to its point of discharge, because a section that runs flat will hold water back even when the pipe is clear.
- Pour water into the drain outlet and time how long it takes to clear.
- Clean the pan and the float, which is the usual cause when AF repeats.
Do not do these
- ×Do not run the unit with AF in place to get cooling. It is a warning code but the water is real and the ceiling above it is not.
- ×Do not ignore a warning code because the lamp stays on. Daikin still asks for it to be checked and repaired.
When to call a technician
No call needed yet, but write it down
Note the date and the exact code, and watch whether it comes back. If it turns into a repeat fault or starts affecting performance, that is when it becomes worth a technician.
- 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.
Clearing the outlet is a homeowner task. The pan and float are a technician job.
What it costs to fix
Parts
Drain pump $80 to $220. Float or drain level sensor $40 to $120.
Labor
One to two hours to clean the drain circuit or replace the pump.
DIY or technician
Clearing the outlet is a homeowner task. The pan and float are 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.