ACiQ mini split error code F6
Compressor phase loss or reversed phase protection.
- TypeProtection
- SystemCompressor / inverter
- Can I fix it?Technician job
- Applies toK-series (ACiQ-K09W-HP…, TCL-built)
What F6 means on a ACiQ
One compressor phase is open or the phases are in the wrong order.
On this platform, F6 is a protection: the system stopped or throttled itself to prevent damage; many clear on their own once conditions return to normal.
Common causes
- A loose or burned compressor terminal.
- An open winding.
- A failed inverter output.
How to fix it yourself
Do the reset and the visual checks, but the underlying repair needs a technician with a meter and the service manual.
- Reset the system: switch the breaker (or the outdoor disconnect) off, wait a full five minutes so the boards fully discharge, then switch it back on and restart from the remote.
- With power off, check the compressor terminal cover for loose or scorched connectors.
Switch off power at the breaker before opening either unit. Capacitors in the outdoor unit hold a charge for several minutes after power is cut.
When to call a technician
Technician job.
Which ACiQ units show F6
This page applies to ACiQ Standard single-zone (ACiQ-09Z-HP…B / W-HP) and multi-zone and K-series (ACiQ-K09W-HP…, SZDM / WHP / KZHP) units on the K-series (ACiQ-K09W-HP…, TCL-built). ACiQ's own documentation lists F6 as "Compressor phase loss or reversed phase protection", the same definition used across the TCL platform it is built on. If your unit shows a code with a different shape (for example a four-character code, or a plain number), it is from a different table; use the lookup with your exact code.
Where ACiQ shows this code
K-series (ACiQ-K09W-HP…, TCL-built): The indoor display shows the code in place of the set temperature. E codes are faults: something has failed and needs diagnosis. P, H, d and F codes are protections: the system stopped or throttled itself to prevent damage, and many clear on their own once conditions return to normal.
Other ACiQ codes
Same part of the system as F6:
F6 on other brands
The same characters do not always mean the same thing. Check the brand on your unit.
- Pioneer F6 Zone F indoor coil outlet sensor (T2B) fault, shown on the outdoor display
- Blueridge F6 Overload frequency limiting (protection)
- Zone Air F6 Compressor phase loss or reversed phase protection
- Daikin F6 High pressure in cooling (refrigerant overcharge)
Questions people ask
Can I reset a ACiQ F6 code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If F6 comes back, the fault is real and needs the checks above.
Is it safe to keep running a ACiQ showing F6?
Not repeatedly. A protection code means the unit stopped itself to prevent damage, and resetting it over and over can turn a cheap repair into a compressor failure. Reset once, check the basics, and stop if it returns.
What will a technician check for F6?
Technician job. Ask for the measurements, not just a parts quote.
Sources
- ACiQ Standard Single-Zone Mini Split Service Manual (SZ-Z-HP / W-HP), Quick Maintenance by Error Code
- ACiQ Mini-Split Air Handler and Condenser Service Manual (MS-SZDM / WHP / KZHP), error code table
Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.