Hey I'm with you but you're going to get some idiot on here saying that you shouldn't leave your dog. Skip the post or just tell em' where to go ;)
Anyway,, I have it covered the best I can,
I have a USB dongle I got off E Bay that sends an E mail or text if the temp goes over a preset limit. It's got about a 3 foot cord with a sensor on the end of it. I stick it in the A/C vent. I don't recall the brand. I bought it years ago. 30 bucks if I recall. Came with a disk to load the software.
Maybe this one:
USB sensor with softwareRemember that doesn't do anything if the power is off and/or the WiFi is down so I use the "teamviewer" app on my phone. It's free. I just run the USB temp reading software on the PC before we leave and log in with teamviewer on my phone and check on them that way. If I can't log on, the power could be off or the WiFi is down. I'd go back and check.
I also always set the temp way down too. You're main problems with A/C (other than a power failure) are at start up. I stick it on 60 and leave. I don't think it ever shuts off. It gives them a "jump" on the heat it the power was to fail. Might be a little cold but they're dogs and cold is better than dead. Search E-bay for USB temp sensor. Teamviewer is free at the app store. Load it on PC and phone.
Another thing I do is stick a digital thermometer in the front window and ask some nice neighbor to glance at it if the wouldn't mind. Then we give them our number. People are mostly animal lovers and don't mind. Last time we camped, a nice lady would text us the temp about every hour. Overkill but very nice of her.
Amazon sells a 12 volt alarm that closes a built in relay that you wire up and program. I have one hooked to a buzzer that's mounted under the font grill. Might pizz off a few campers it they had to listen to it for a while but might also save my dogs. I can always say "sorry"
;)
Amazon link