DIY HVAC Tools

Goodman mini split error code A1

Indoor unit control board (PCB) failure.

  • TypeFault
  • SystemControl board
  • Can I fix it?Technician job

What A1 means on a Goodman

The indoor control board failed its self-check or could not read its memory.

On this platform, A1 is a fault: something has failed or is disconnected and needs diagnosis.

Common causes

  • A surge or lightning event.
  • Water on the board from a blocked drain or a leak.
  • A failed 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.
  2. If the code comes straight back after a reset, the fault is real and not a glitch.
  3. Look for water tracks or corrosion in the indoor electrical box.

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 replacement by a technician.

Which Goodman units show A1

This page applies to Goodman e-Series wall-mount (FTXNG indoor / RXNG outdoor) units. Goodman's own documentation lists A1 as "Indoor unit control board (PCB) failure", the same definition used across the Daikin 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 Goodman shows this code

Most Daikin wall units do not show the code on the unit; the operation lamp blinks. To read the code, point the remote at the unit, hold CANCEL (or Timer Cancel) for about 5 seconds until 00 shows, then press CANCEL repeatedly. Each press shows a code; when the unit gives a long continuous beep instead of two short beeps, the code on the remote is the stored fault. Units with a wired controller show the code directly. A and C codes are indoor-unit faults, E, F, H, J, L and P codes are outdoor-unit faults and protections, and U codes are system-level problems such as communication, power supply and refrigerant shortage.

Other Goodman codes

Same part of the system as A1:

E1Outdoor unit control board (PCB) failureH0Compressor sensor system (voltage or current) faultH3High-pressure switch faultH8Compressor input current (CT) system fault
00No fault stored (normal)A3Drain water level abnormal (float switch)A5Freeze-up protection (cooling) or high-pressure control (heating)A6Indoor fan motor fault (locked or abnormal)A9Indoor electronic expansion valve (EEV) faultC4Indoor heat exchanger (liquid pipe) temperature sensor fault (open or short circuit)C5Indoor heat exchanger (gas pipe) temperature sensor fault (open or short circuit)C7Front panel (open/close) drive fault

All Goodman error codes

A1 on other brands

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

  • Daikin A1 Indoor unit control board (PCB) failure

Questions people ask

Can I reset a Goodman A1 code myself?

Yes. Turn the system off at the breaker for five minutes, then restart it. If A1 comes back, the fault is real and needs the checks above.

Is it safe to keep running a Goodman showing A1?

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 A1?

Board replacement by a technician. Ask for the measurements, not just a parts quote.

Sources

  • Goodman e-Series product documentation (FTXNG / RXNG models)
  • Daikin residential (RA) service manuals (error 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.