DIY HVAC Tools

Rheem mini split error code U5

Whole-unit current detection error.

  • TypeFault
  • SystemControl board
  • Can I fix it?Technician job
  • Applies toFloating Air series (Friedrich-built, Gree platform)

What U5 means on a Rheem

The outdoor board's current-sensing circuit is returning an impossible value.

On this platform, U5 is a fault: something has failed or is disconnected and needs diagnosis.

Common causes

  • A failed current sensor or board.
  • A loose connection on the board.

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.

  1. 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.

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

Board-level fault for a technician.

Which Rheem units show U5

This page applies to Rheem Classic and Classic Plus wall-mount (RIWH / ROWH), Endeavor Line multi-zone and Floating Air series (2023 and later) units on the Floating Air series (Friedrich-built, Gree platform). Rheem's own documentation lists U5 as "Whole-unit current detection error", the same definition used across the Gree 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 Rheem shows this code

Floating Air series (Friedrich-built, Gree platform): The code shows on the indoor unit's display in place of the temperature. If the display is off, press the Light button on the remote. Some models also count out the code as indicator blinks. E codes are system protections and faults, F codes are mostly sensor faults, H codes are outdoor and compressor protections, U codes are motor and valve faults, and P codes are power-supply faults.

Other Rheem codes

Same part of the system as U5:

E:22Indoor unit capacity setting errorE:32Indoor unit main board faultE:35Manual auto switch errorE:62Outdoor unit main board fault (EEPROM)E:84Current sensor faultE:86Pressure sensor or pressure switch faultEEEEPROM (memory) error on a control boardC5Jumper cap malfunction (missing or wrong jumper)
E:11Serial communication error between indoor and outdoor unitsE:12Communication error with the wired remote controllerE:23Indoor and outdoor unit combination errorE:26Indoor unit address setting error (multi-split)E:29Number of connected indoor units errorE:41Indoor room temperature sensor fault (open or short circuit)E:42Indoor heat exchanger (middle) temperature sensor fault (open or short circuit)E:51Indoor fan motor fault

All Rheem error codes

U5 on other brands

The same characters do not always mean the same thing. Check the brand on your unit.

Questions people ask

Can I reset a Rheem U5 code myself?

Yes. Turn the system off at the breaker for five minutes, then restart it. If U5 comes back, the fault is real and needs the checks above.

Is it safe to keep running a Rheem showing U5?

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.

What will a technician check for U5?

Board-level fault for a technician. Ask for the measurements, not just a parts quote.

Sources

  • Rheem RIWH / ROWH Ductless Design and Technical Manual (RIWH18ASJ to RIWH36AXJ)
  • Rheem Classic Series ductless installation manual 9318739237 (Fujitsu General document number)
  • Friedrich Floating Air Select Service and Parts Manual (2015-2019), diagnostic 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.