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A503

A503 - Time clock not advancing time properly

Rheem · Air Conditioning

What does A503 mean?

The time clock feature is not functioning correctly, meaning the time is not advancing as it should. This could be a controller issue.

Common Causes

  • Time clock malfunction
  • Controller issue

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the programming of the time clock.

  2. 2

    Reset the unit by unplugging it for 30 seconds and plugging it back in.

  3. 3

    If the problem continues, the controller may need replacement.

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