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H99

H99 — Indoor heat exchanger freeze prevention

Panasonic · Aquarea Heat Pumps

What does H99 mean?

The indoor heat exchanger freeze prevention mechanism has activated, typically due to dangerously low temperatures within the heat exchanger.

Common Causes

  • Problem with the indoor heat exchanger.
  • Refrigerant shortage in the system.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Ensure the indoor unit area is not exposed to excessively cold drafts or temperatures.

  2. 2

    Check that the water pump is operating correctly and water is circulating properly through the heat exchanger.

  3. 3

    If the error persists, contact a qualified technician to check for refrigerant shortage or to inspect the heat exchanger.

Browse all codes in this manual (77)
Verified technical data. Last updated: April 2026

Related Faults

2 beeps then pause2 beeps then pause - Overfill warning3 red flashes3 red flashes - Communication errorAbnormal operationAbnormal operation — Solar pump cable issue
Source: Panasonic Aquarea Heat Pumps
Open Manual (Page 93)Search more codes in this manual