I was driving home today and this thought came into my head....does the a/c maintain temp by adding heat to the cold or by decreasing compressor activity.
So, what I am asking is if it is 80 outside and you have the a/c set for 72 is heat added to maintain 72 or, does the compressor cycle less.
My thought is that if it is simply a matter of heat being added to the air, you can run it as cold as you like, no need to keep it at 76 to save gas, 66 would burn as much as 86.
If the compressor cycles less, that would save gas and electricity wouldn’t it.
Here is where I am going, to the people that are having battery problems in the heat, would running a colder temp at a lower fan speed conserve the battery.. drop it into 2 to prevent a idle drain when the compressor goes into electric...anyway, I do understand the engine and electric operation of the compressor, this is more curious if anyone knows.

 

In most cars, Hybrid or not... warm air is added to the cold air conditioning to give a moderate temperature.

Hence, I run mine at full cold for the fewest number of minutes, then manually turn it off and turn it back on when needed.

It is a pain in the rear, but, saves gas by putting less load on the engine.

 

I agree: A/C runs full cold, all the time. Temperature is adjusted by mixing in warm air. The only thing: if you set the thermostat warmer, at least with auto thermostat, I would think the compressor is going to cycle on less often.

MSantos suggests, when starting out with a hot car interior, say from sitting in the sun: start with high thermostat temp, 26~30, and then gradually drop it down, adjusting donward in intervals that avoid racing fan speeds, till you settle on a comfortable ambient temperature.

Personally, we use AC very little, but then we're in a pretty temperate climate.

 

NO!

Always put the temperature to the coldest setting for best efficiency.
Slow down the blower (fan) to make the A/C compressor to run less often.

The faster you remove the "coolness" (higher blower setting) the more the A/C compressor needs to run.

Never "mix" the temperature, unless you are lazy!

However, setting it to moderate temperature instead of full cold will cost you only 1-2 MPG. So determine what it is worth to you for the convienience.

 

If I understand it right you must do the opposite on the hch2.
msantos really knows what hes talking about and me thinks I understand why you must start the climate control thingy in the highest temp then dial it down.
the hch2 got this engine and electric compressor and you should stick to the electric part to be more efficient. if you crank the temp too low then the engine will start helping the electric and both start pumping hard together and that kills the fuel economy . from what I understand the engine driven compressor assists the electric part when temp is to low.
anyways,I tried it and it works so the advice makes a whole bunch of sense to me.

ks

 

Maybe the waters are being muddied by the HCHII's auto climate control: you can sort-of control the fan speed by adjusting temperature: set temp higher, fan will slow down. But if you dial in a fan speed (as GPSMan1 suggests) you override the auto, and then setting temp lowest is likely ok, ie: not making the fan race.

Still, the one thing that will reduce AC's impact on fuel economy is reducing the time/frequency the compressor is actually running. To that end, I think leaving fan speed on Auto and dialing in a higher temp setting is one effective way to reduce compressor running times.

 

That makes sense and almost nobody will deny that
But cranking the temp down and hope for better mpg is the thing of fables in the hch2 cause it just kicks the compressor faster than it needs to anyways. that's bad.

just test it. dial a lower temp and set the fan by hand to low rpm and you will see. The engine compresser is still helping the electric and the engine does not even autostop. makes no sense to me to cheat the good tech in this car and put the hch2 on low temp setting unless youre lazy and hate good mpgs.

ks

 

Per the service manual for my HCH 07, the climate control will vary from running both the belt driven and electric compressor in high temperature / maximum cool down situations, to only running the belt driven compressor in moderate temperature situations with higher blower fan speeds, to running AND varying the speed of the electric compressor in temperature maintenance situations and low blower fan speeds. (I've even seen in these low load situations a single bar of forced charge while cruising, presumably to run the electric compressor).

I would set the temperature to what you want it to be at, and let the the AUTO logic do the best thing for the car with the A/C on. When its cooler out, i always force the A/C off, except to run it every other week to keep the a/c system lubricated.

 

Kevin, you missed my point. I said, or was trying to say, running it COLD for fewer number of minutes (IE get your car comfortable ASAP) and then turn it off is better than running it at "medium" for a long time, or continuously.

I base what I say on laws of physics, it does not matter what car you drive.

 

One thing I've started doing, on the semi-rare occasions we use AC, if traffic is stop-and-go and/or I'm stuck at a red light, and Auto-Stop has activated, I'll just shift to neutral and shut the engine completely off (Forced Auto Stop), to avoid the AC running off the battery pack. It's typically only a minute or two, things don't really start to get steamy that fast.