i would probably do it with two+ automations. Something like:
ON
automation:
- trigger:
time pattern
- beginning of every 3 hours
- then:
- start timer with duration 37 minutes (select your timer helper)
- Turn on AC unit
OFF
automation:
- trigger:
Manual Event
- event type:
timer.finished
(case sensitive!) - event data :
entity_id: timer.[timer_helper_entity]
- event type:
- then:
- turn off AC unit
STARTUP_CHECK
automation:
- trigger:
- when home assistant is started
- if:
state
- timer helper isidle
- AC is on
- then:
- turn AC off
Note 1: make sure the timer helper has restore state and time when HA starts
enabled
note 2: automations using the timer.finished event will not trigger on startup if the timer expires when Home Assistant is not running.
note 2a: the third automation is for your edge case that you reboot/shutdown HA when the OFF
automation was supposed to fire. it should ensure the AC turns off after the timer was supposed to be finished and HA is started. this automation does not account for if the AC is turned on manually and you restart HA.
i can get you the .YAML or pictures when I’m at a computer.
I was never able to get this to work properly… my mouse cursor always just disappears. 🙃