Quote:
Originally Posted by EcoCivic
Saving even 10% power running the AC would be significant IMO, and I'm pretty sure the efficiency gain would be larger than that. Not only does the car cool down quicker and the compressor runs less, the compressor takes less power while it is running because the head pressure is lower.
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From this perspective, the question lies in the amount robbed from the available motive force. With less power applied to move the vehicle, the cooling system steals a larger piece. Maximizing the leverage of the phase change circuit will net only a few percentage points of efficiency. After that, the level of comfort will be affected.
Running lower system pressures and or compression ratios will decrease power draw. This comes at the expense of reduced cooling system capacity. Not much of an expense in less tropical climates, but the closer we get to the equator, or the middle of the summer, the more insufficient the reduction in capacity becomes at satisfying comfort. This effect has a way of rearing its head on a holiday weekend in gridlocked traffic.
Hardcore options are plenty, but it all boils down to a personal decision: where does the need for comfort outweigh the performance? Sweating like a pig during the rare occasion pays large dividends the rest of the time.