CodeRegistry
Brands
  1. Home
  2. Rheem
  3. Air Conditioning
  4. A904
About·Privacy·Terms

CodeRegistry — Your global library for technical solutions.

For your safety: always follow the equipment manufacturer’s official manuals. CodeRegistry is an independent help site and is not affiliated with the brands listed here.

A904

A904 - Controller fault: Call Tech Service

Rheem · Air Conditioning

What does A904 mean?

The controller is experiencing a fault. This is a general error message indicating that technical service is needed.

Common Causes

  • Controller malfunction
  • Internal electronic fault

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check that the unit is properly powered.

  2. 2

    Try resetting the unit by turning the power off and on.

  3. 3

    Contact technical service for diagnosis.

Browse all codes in this manual (48)
Verified technical data. Last updated: April 2026

Related Faults

1 beep1 beep - WiFi Soft Reset initiated3 beeps3 beeps - WiFi Hard Reset initiated3 red flashes3 red flashes — Communication error
Source: Rheem Air Conditioning
Open Manual (Page 34)Search more codes in this manual