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For about 4 weeks, my AC has been giving me problems at an idle. In the past, it would blow nice and cold all through the RPM range. Lately, if at an idle for more than a minute, it would blow that warm, muggy air like the compressor kicked out. I could never see that the clutch disengaged, and I had it checked at a local shop and they said all was well, but the problem persisted. They replaced the low-pressure switch [i think just so they could charge me for something], but no change. We took a trip to the Rockies towing the 5th wheel last week and it was acting up at rest areas etc.

We got back home on Sunday. Tuesday morning the batteries were dead. Did some troubleshooting and found one of the batteries [OE] dropped at least one cell, probably two [wouldn't charge past 8.5 volts].

I replaced both batteries on Tuesday night, and after horsing around to get the HVAC motors recalibrated Tuesday night and Wednesday, the AC issue hasn't resurfaced. It's blowing cold at an idle like it used to.

I'm wundering if the one bad battery made it so the voltage/amperage wasn't adequate to fully engage the AC clutch, giving the appearance it was turning the compressor properly etc. etc.

Thought it might be useful experience for others trying to troubleshoot AC issues at idle. Of course it could all be a coincidence and I just wasted your time by posting this, but I hope not.
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