Sounds like a leak to me somewheres also. I had a similar system in my Venture, ( but not in my Roadmaster.) The system developed a leak and the compressor would go on when the level got too low, and then stop once the proper level was achieved. This occurred whether the van was running or not, (scared a few people in parking lots as they walked by the van as the compressor went on
with it's "growling" noise.) I eventually pulled the fuse to the compressor. It never really drained my battery, perhaps because either the vehicle was used everyday and didn't have the chance to fully discharge the battery, or the leak was so minor and the compressor not operating that much to drain the battery, and the battery being in good condition and able to withstand the minor draw from the compressor.
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