Sorry, Bart. I guess my thought was kind of: Well, he just asked about the AC, and I think his question has been answered. So I'll just follow Jules' lead and use it to mock S10's because I hate them. :/
And I do hate them. Mehgan, I would pose the same question to you that I would most people who say 'look how many miles I've been able to rack up on this vehicle you think sucks'...do you have 100% of the history on it? And it's never had a major repair? If the answer is 'yes,' well...I don't believe you.
When someone says 'look, my Corolla has 250k, and I never really even did maintenance!'...I believe them. I've seen some old Toyotas survive some stunning neglect. With an S10/Blazer of that era...I have severe doubts. The trans has never been pulled to address the front pump issue? Never needed a rear main seal? Every engine accessory (AC compressor, alternator, power steering...) hasn't died at least once? Never had the intake off? If you've had to give it a constant stream of money to keep it going, I can't see calling it reliable. Going back to a beater 4cyl Toyota as a comparison, a lot of those cars have never had anything taken off of the engine aside from the valve cover. That's a big difference.
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OP, if you want help diagnosing your charging system, I'll gladly help you, FWIW. You probably do have a slight issue if you're idling it for an hour a week and the battery is repeatedly going dead.
For one, I would say 'don't idle it.' Drive it. Take it to work one day a week or something.
Two, realize that your battery is fighting a war of attrition. A minor charging issue could take months to manifest itself as a problem. E.g. Batt is 100%...vehicle sits, batt discharges to 90%...vehicle starts and runs, batt ends up around 95%...continue with a similar pattern. Said pattern would be further exacerbated by a battery that was never fully-charged to begin with (they rarely are). It might take a good long while before it actually ceases to start.
I'd start with the basics, though. Let the parts store fully charge the battery and do a quick test. Make sure your connections are good when you put the battery back in. Side posts don't tend to suffer from the layer of corrosion that can inhibit top posts. If the terminals/cables look okay, they're probably okay. Just make sure the bolts tighten up- if they spin, someone may have stripped out the threads in the battery. Or just the posts. And if the bolt heads on the posts are chewed up from someone using the wrong tool, get some new ones (...and a 5/16 wrench).
Past that, I'll go to what I always say: get a voltmeter. Check charging voltage, check v-drop across cables when starting.
