Air Conditioning - Gas Mileage Effects - S60 Topic is solved

[Guest]

Can someone explain how the compressor cycles when the AC is turned on - If the AC is on, the knobs turned CCW all the way to cold, I assume the compressor is continually running. When you back off the knob in the CW direction, I'm guessing one of two things happens: 1. The compressor runs just as much but warm air is allowed to mix in or 2. The compressor cycles less often, allowing for better gas mileage. Any insights? Thanks in advance.

[potroast]

even when the AC is on full-blast, you will not be using the compressor all the time. The compressor will cycle on/off as needed. It is regulated by how much pressure is in the system. When pressure drops below a set threshold, the compressor kicks on until pressure reaches another threshold.

The more you use the AC, the worse your fuel economy will be. I have also noticed that I can feel the lag on the engine when the compressor is on. I have also noticed that when doing "performance" (high-rpm) driving, the AC is not as cold because the AC clutch has been activated. Ironically, my AC is coldest when cruising around 2k RPM.

But yes, when comparing "full-blast" AC operation to "low" operation, you will receive better gas mileage at the "low" setting. Likewise, best gas mileage is actually obtained with the AC off.