On mine you can certainly hear it when its on. Is it an electric compressor, or does some wheely thing engage with the drive belt?
I have often wondered how the cool air is created. I guess a fridge has an electric compressor.... is it the same for a car?
Please bear in mind the AC system has benefits above and beyond just keeping the car cool during hot weather.
The system also dries the air in the car, eliminating condensation in cool damp weather as well as helping to keep the driver more alert in all weather conditions.
I'm not sure about the Up, but it is normal for car AC systems to shut down automatically when the outside temperature falls below 4 degrees centigrade. I always keep the AC system on all the time, partly due to the benefits above, but also because it helps to maintain the system in the best condition for the long-term. The refridgerant also lubricates the compressor, so when the system is on it keeps the system lubricated and helps stop corrosion in the compressor/system. AC systems can be expensive to repair, so a small increase in fuel consumption is likely to be cheaper in the long run, even without the benefits it offers year-round.
Whilst on the subject of AC, some manufacturers give the impression that system is sealed and needs no maintenance, but this is not really the case. Over time refrigerant leaks through the seals in the system at the rate of c.10-15% of total volume per year. It is therefore sensible to get the system serviced/re-charged every couple of years to maintain peak performance.
As this forum is read by a wide range of people, some with limited interest in technical issues, I hope the above is useful info. For those with more technical interest - it's not aimed at teaching you to suck eggs!
And the system will, over time, grow bacteria in the fluids, leading to a bad smell all of a sudden. Which means a trip to the garage to get the system re-charged and checked over.
It's best to switch on the air con at least once a week for ten minutes or so just to keep it exercised, although this advice is something I've failed to follow with my current StreetKa. My excuse is that I work a shift pattern so I don't need to chill the air inside the car that often when driving to and from work. It gets more use in the winter to warm me up.
My aircon makes more noise when the fan is on setting 1. You can hear it doing something, bit like a faint bubbling/motorish grumble. When the fan goes to 2 it just dies away. Sometimes on setting 1, it doesn't make any noise. I wonder what that's all about..
Hi, the gurgling you can hear is the high pressure gas going through the expansion valve. you know when you spray an aerosol for a long time, then nozzle gets cold, how the expansion valve works. it sprays the high pressure gas refrigerant through it and then it becomes a freezing cold gas and then turns into liquid in the evaporator coil (which gets very cold. about 2 degrees).the blowers then blow the air through it and it absorbs the heat and moisture out of the air... the liquid tehn becomes hot and goes to the condenser coil and air is blown over it to get rid of the heat! then its off to the compressor which squeezes the gliquid back into a gas as it heads off to the expansion valve again!
I used to switch it off when I was going to need a bit more power in my Fiat Seicento Sporting, such as the M6/A14 interchange. I called it my "turbocharger" but I doubt it had that much effect, more psychological.