ACiQ mini split error code P9
Compressor drive abnormal load protection.
- TypeProtection
- SystemCompressor / inverter
- Can I fix it?Technician job
- Applies toK-series (ACiQ-K09W-HP…, TCL-built)
What P9 means on a ACiQ
The drive saw a load on the compressor it could not regulate.
On this platform, P9 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 failing compressor.
- Liquid refrigerant flooding the compressor.
- A failed inverter drive.
- Unstable supply voltage.
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.
- If you own a multimeter and are comfortable using it, measure the supply voltage at the outdoor unit's L1 and L2 terminals with the unit running. A 230 V system should read roughly 208 to 253 VAC.
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 diagnosis of the drive and compressor.
Which ACiQ units show P9
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 P9 as "Compressor drive abnormal load 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 P9:
P9 on other brands
The same characters do not always mean the same thing. Check the brand on your unit.
- Blueridge P9 AC contactor protection
- Zone Air P9 Compressor drive abnormal load protection
- Mitsubishi Electric P9 Indoor pipe (condenser/evaporator) temperature sensor fault (open or short circuit)
- Trane P9 Compressor drive abnormal load protection / Indoor pipe (condenser/evaporator) temperature sensor fault (open or short circuit)
Questions people ask
Can I reset a ACiQ P9 code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If P9 comes back, the fault is real and needs the checks above.
Is it safe to keep running a ACiQ showing P9?
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 P9?
Technician diagnosis of the drive and compressor. 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.