When we leave our dog in the motor home, we worry about the A/C failing. I do have an temperature monitor that sends a reading to an excel spreadsheet that I can view on my phone. Well,, if I have service.
Where we camp, we know everyone and the RV is unlocked so I'm installing a monitor with a buzzer so our friends can save the dog. You can set it so it goes off at whatever temp you set it for. Note that it reads in Celsius and it's 12 volt DC.
Here's what I bought:
MonitorI have the buzzer.