Panasonic mini split error code F91
Refrigeration cycle abnormal (low charge or blockage).
- TypeFault
- SystemRefrigerant circuit
- Can I fix it?Homeowner checks, then maybe a tech
What F91 means on a Panasonic
The outdoor board concluded from temperatures that refrigerant is not flowing as it should: low charge, a closed valve or a restriction. On a new installation this points to a flare joint that did not seal or a service valve left closed.
On this platform, F91 is a fault: something has failed or is disconnected and needs diagnosis.
Common causes
- A leaking flare joint.
- Service valves not fully open.
- A kinked line set.
- A genuine leak on an older system.
How to fix it yourself
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician.
- Open both service valves fully.
- Leak-check every flare joint with soapy water while the system runs.
- Inspect the line set for kinks.
- Anything inside the refrigerant circuit (sensors are fine, but valves, compressors and leaks are not) needs EPA-certified refrigerant handling. That is a technician job.
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
A technician must find the leak, repair, evacuate and recharge by weight.
Which Panasonic units show F91
This page applies to Panasonic Exterios, ClimaPure and Multi-zone (CU-xE) units. Panasonic's own documentation lists F91 as "Refrigeration cycle abnormal (low charge or blockage)", the same definition used across the Panasonic 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 Panasonic shows this code
The indoor unit blinks its Timer lamp when a fault is stored. To read the code, point the remote at the unit and hold the CHECK button (on the back of the remote, under the flap on most models) for about 5 seconds until -- shows, then press the temperature up or down button; each press shows a code, and the unit beeps continuously (not a short beep) when the code shown is the stored fault. H codes are faults (a sensor, motor or board that needs attention). F codes are protections: the outdoor unit stopped itself because of pressure, temperature or current.
Other Panasonic codes
Same part of the system as F91:
Questions people ask
Can I reset a Panasonic F91 code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If F91 comes back, the fault is real and needs the checks above.
Is it safe to keep running a Panasonic showing F91?
The unit will usually refuse to run, or run with reduced output, until the fault is cleared. Repeated resets do not fix anything and can mask a problem that is getting worse.
Do I need a technician for Panasonic F91?
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician. A technician must find the leak, repair, evacuate and recharge by weight.
Sources
- Panasonic residential split service manuals (H/F code tables)
Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.