5378 - Bosch Heat Pump Z1 failed defrosting warning

What does 5378 mean?

This warning indicates that Bosch Heat Pump zone 1 has failed its defrosting cycle. It triggers if the condenser temperature (TR24) is below 25°C or pressure sensor (PH1) is below 30°C after 800 seconds in defrosting. This warning activates after 3 occurrences in 3 hours, or if conditions are active for 30 minutes.

• Ice buildup on the outdoor unit's evaporator.
• Malfunction within the defrosting system components.

Click steps to track your progress.

1. 1

   Visually inspect the outdoor unit's evaporator for any ice buildup.

2. 2

   Carefully remove any visible ice using warm water; avoid chipping or scraping with sharp objects.

3. 3

   Ensure that there is adequate airflow around the outdoor unit, clearing any obstructions like snow or leaves.

4. 4

   If the warning persists, contact a qualified technician to inspect the defrosting system.