Zzzow!

The weather is starting to take a turn for the worse up here and I will soon have to put my Z in hibernation, but not yet!! Anyways, it's like upper 40's lower 50's and whenever I start the car, the AC is always on. I have to manually turn it off. I have the temp set at 75 and the fan on auto. Anyone else experiencing this or anyone with a suggestion?

z350z

The light for the AC won't go out, but I am assuming (not sure though) that it doesn't run the compressor unless it needs to. Usually in cars with climate control, you don't have to worry about turning the AC on and off (which is kind of the point of climate control) and in my other car I never do. I hope it doesn't use much power for the AC when the temp is cool enough that it is not required.

Can anyone confirm this?

raceboy

I am pretty positive that as long as that light is on, it's running. I think that because if I turn it off, regardless of temp, I get fogging in the car on vent and not recirc.

fdao

Huh? I could just turn off/on my auto A/C whenever I need to. It doesn't need to be turned off each time the car is started .

roberto350z

mine just turns off too!!!!

integraowner

1) I think the A/C is running all the time if the light is on. The compressor turns on/off as needed, just like when it's hot outside. It's just that when it's cooler, the A/C is operating as a dehumidifier rather than a cooling device. Hence the name "air conditioner" rather than just "air cooler".

2) I haven't quite figured it out. But I found the fact that the A/C turned on (and it makes a stupid lame sounding noise when it powers up, ruins the initial idling rumble of the engine lol). Anyway, I'm rambling. It seems like if I turn the car on, manually turn off the A/C, then the next time I turn it on the A/C is off. I think I had to have everything that's "auto" be off.

3) I'm not impressed with the performance of the "auto" climate control at all. The positioning of the temp. sensor is retarded... I was driving around and noticed that whenever warm sun was on the sensor (which is exposed via the windshield) it cranks up the cooling, even though the cabin was already cold enough!

4) The Z generates a lot of heat. Maybe that's another reason why the A/C comes on by default - because in most temps about 50 the car generates enough heat that you need the AC cooling if you want to maintain a cool cabin temp. I find I have to set my thermostat closer to 60 than to 75 (75 is what they recommend in the owners manual) in order to maintain comfort.

5) followup to 4 above - even if I crank the thermostat down to 60, with the A/C off, the incoming air is SIGNIFICANTLY warmer than the outside ambient air temp. This sucks. I expect my outside air to be nicely filtered then fed into the cabin at nearly the outside air temp, not 15 degrees warmer! damnit!

Do you guys experience the same stuff?

MannishBoy

iTrader: (1)

I suspect integraowner's number 1 is the real answer. My Pontiac AC is always on until the temperature goes to around 40 degrees (although you can override it). It is on to dehumidify the air.

Dr Bonz

iTrader: (1)

Am I missing something? All you do to turn the AC light off is push the button in and the light goes out. Is that what you mean?

roberto350z

thats what I do. Turn the light off by pushing the middle. But, if you switch to recirc, the A/C will turn on, and you cannot turn the A/C off and be on recirc mode

D'oh

I don't use the auto features of the AC since I'm a control freak, so I can't shed any light on its performance. However, I also notice that the incoming vent air is quite a bit warmer than the air outside. Probably because the air is getting sucked in near the engine, and because the vents are always heated up by the sun and warm the air a bit before it gets into the car. I'll have to see what it's like in the morning when I start up and everything is cold.

-D'oh!

z350z

Yes, you can turn it "on" or "off" as indicated by the green LED easily by pressing the button. But my question was: when it is "on", does the climate control system really run the compressor full blast even if it's freezing cold outside? The point of a climate control system is that it's thermostat-based and applies heat and cooling as required so that you don't have to fiddle with the temp controls all the time. So I was wondering if it's smart enough to not put much energy into the compressor if it doesn't need it. But based on some of the messages above, I think I would agree that it still performs some dehumidification in certain conditions even if it's not cooling. But if it's really cold and dry out, does it really use any extra energy?

Does everyone actually use the A/C button to turn it on and off based on temp, or do you just trust the climate control system to do its job? I know in my other car, I never use the "EC" (Economy) setting to shut down the compressor. Similarly, I am inclined to just leave the Z's system on and let it do its job, but is that going to cost me power all the time even when cooling is not required? That is the question!

Intrepid

The air conditioning compressor has only two modes: ON and OFF.

You can adjust the speed of the fan and whether air is being recirculated within the cabin or some air is being pulled in from outside (Max v. Econ). But the compressor is either running or it's not (there is no in between).

When you floor the accelerator in a modern car, the computer tells the compressor to turn off, so you have maximum power.

The compressor will usually always be ON in Auto mode, unless the outside temperature drops to below 35 degrees I believe. This keeps the inside of the car dehumidified and prevents fogging. If you don't like this, you are going to have to use manual mode. But if it's too cold, simply turn up the heat!

unho

Yeah i do not like how the ac turns on automatically when i just want some air.

integraowner

I think part of the point was that even though you turn off the A/C with the manual pushbutton, it can magically re-activate itself the next time you start the car.

If it's not going to affect my gas mileage, or cause it to wear out prematurely, I guess I'll try to get in the habit of just leaving it all on and adjust my temp with the thermostat alone. However, sometimes I don't like the system's decision about auto fan speed.

Zzzow!

The reason I started the thread was because I don't want the AC to cool the car when its cold already and I don't want it to sap power when I don't need it. And I was getting frustrated that it wouldn't stay off when I turned the car off/on. At the time though I didn't think about the dehumidification function of it though, which is needed. I guess I'll just leave it on now and see if it blasts out cold air.

z350z

Thanks for the info, Intrepid. Where did you find out these details? Is it in the manual? Or is it just standard behavior for most new cars?

I just leave it on all the time now; it seems to give good results and I don't notice any difference in engine power between on and off.

z350z

It won't blast out cold air if the interior temp is where you set it. That's why I was wondering if it shut the compressor off or used it in a low-power mode or something. It might do that, or it might just compensate by adding heat. In any case, I find the best thing is to never mess with it: set the temp once, leave it on, use Auto (or set the fan speed if auto is blasting the fan annoyingly), and it's always comfortable inside.

John

iTrader: (17)

I too am irritated with the A/C turning on whenever you turn the fan on... By default it should be off, and when in the auto position, have at least a 2 second delay or so. Even at lower temperatures, when you turn the fan on, the A/C will come on (you can hear the compressor kick in).

Zrated

What JDZ said is right. This is out of control. It works like every other air conditioner. When the light is on, the compressor will cycle on and off. A/c air is de-humidified and that is why it works as a de-humidifier on the windshield. Keep the control out of auto mode and the A/C will not come on until you press the button.