Here’s an update to work around this:
alias: Test
description: ''
trigger:
- platform: numeric_state
entity_id: sensor.daikin_schlafz_inside_temperature
above: 21
- platform: homeassistant
event: start
- platform: event
event_type: automation_reloaded
condition:
- condition: numeric_state
entity_id: sensor.daikin_schlafz_inside_temperature
above: 21
action:
- device_id: a3f6afd9854bdd8df4ce64b78db64c8c
domain: climate
entity_id: climate.daikin_schlafz
type: set_hvac_mode
hvac_mode: cool
mode: single
This triggers when the temperature crosses the threshold or when the system or automation is restarted, and the condition ensures that the AC isn’t turned on when triggered by a restart when it’s cold.
I’ve also changed your initial trigger from a device to an entity trigger, as it’s easier when manually editing, although this is just personal preference.