Without SA555 (High Cluster), you can't:

- set time
- see time
- set date
- see date
- see arival time
- change fromt °C to °F
- turn on memo
- turn on aux ventilation
- use the 'code' feature

The Rest should work normaly.


edit:
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To set and see the time, you can install a MID. With a MID connected it works.