Poor Performance With Aircon On

[pixel8r]

Hey,

I've always thought my car is painfully slow in hot weather with aircon on (it is) and that's that, but lately I've been noticing that it can be ok if I start the car with aircon switched off and just turn it on after idling for 10 seconds or so.

I'm not sure what the difference would be but when aircon is on when the car starts, it just seems to put a lot of strain on the engine and the car seems to struggle a bit. It also takes longer to reach boost since it wont rev anywhere near as quick...but will start to boost at around 2500rpm as per normal, only its more pronounced and sudden compared to with aircon off.

Anyone know why

(1) its so painfully slow with a/c on (maybe the extra a/c fan is sucking up too much power? it seems to be on quite often)

(2) it seems faster when a/c is turned on (by pressing the button) a few seconds after the car starts rather than being already on when the car starts.

could it just be a sensor or something??

btw, even when a/c is already on (ie. the light is on) when the car starts, it doesn't actually fire up the a/c until about 1 second after - presumably to go easy on the starter motor, so its nothing to do with any extra strain from the a/c clutch when starting or anything.

Edited January 8, 2008 by pixel8r

[avrahan]

Edited January 10, 2008 by avrahan

[Stinky Rooster]

I would be looking at the air con compressor clutch. There is a chance that the throw out arms on the inside of the clutch could be dragging their feet due to incorrectly aligning if the clutch is engaged at startup (the crank nose on many 6 cyl engines has been known to "wander" about a bit at start up) It could also be causing the main spindle of the compressor to "pole" out if it is a bit worn.

The moral of the story, is i would be looking at the compressor before anything else.

[pixel8r]

I would be looking at the air con compressor clutch. There is a chance that the throw out arms on the inside of the clutch could be dragging their feet due to incorrectly aligning if the clutch is engaged at startup (the crank nose on many 6 cyl engines has been known to "wander" about a bit at start up) It could also be causing the main spindle of the compressor to "pole" out if it is a bit worn.

The moral of the story, is i would be looking at the compressor before anything else.

Thanks - will get it checked out when I can

[Appealing]

Aircon sucks up to 10kw of power. You should'nt have it on when starting due to the extra draw on the starter. In extreme conditions you can start blowing fuses, (unlikely but doesn't do the car any good).

[ssshonky]

if your sitting there with the motor started and the a/c off. . when you switch the Ac on does it bump the idle up a bit? if not your AAC valve might not be working 100%

[pixel8r]

Aircon sucks up to 10kw of power. You should'nt have it on when starting due to the extra draw on the starter. In extreme conditions you can start blowing fuses, (unlikely but doesn't do the car any good).

um...not applicable to the stagea - see my original post.

As I explained, the stagea wont actually start the a/c until a couple seconds after the car starts, so the starter motor knows nothing about the a/c. Basically Nissan made sure this wouldn't happen.

What I'm talking about is the fact that there seems to be a slight difference depending on WHEN I turn the A/C on....weird...but maybe I'm just being too picky?

I've also been led to believe that the so called extra stress on the starter motor due to a/c being on is mostly just a myth in todays cars...

[pixel8r]

if your sitting there with the motor started and the a/c off. . when you switch the Ac on does it bump the idle up a bit? if not your AAC valve might not be working 100%

Not sure if it does or not...will check this arvo when I finish work. I can definitely tell its engaged the a/c pump etc but not sure about revs - pretty sure it still idles at ~700rpm with a/c on, and has been known to dip for a split second before, making the car give a quick shudder....extremely rare though.

I've heard about the AAC valve, just didn't realise it would be related to this?

Whereabouts is it located and what would I look for to check?

[Stinky Rooster]

um...not applicable to the stagea - see my original post.

As I explained, the stagea wont actually start the a/c until a couple seconds after the car starts, so the starter motor knows nothing about the a/c. Basically Nissan made sure this wouldn't happen.

What I'm talking about is the fact that there seems to be a slight difference depending on WHEN I turn the A/C on....weird...but maybe I'm just being too picky?

I've also been led to believe that the so called extra stress on the starter motor due to a/c being on is mostly just a myth in todays cars...

I dunno about the S2, but in my S1, when you floored it, 2 things happened - the trans automatically switched to "power" mode, and it shut the aircon off until you lifted. The ECU in the stagea's never ceased to amaze me how intelligent it could be with things like that.

As for checking the aac valve, try this

http://www.skylinesaustralia.com/forums/Di...html&hl=aac

but my understanding of it, is that if this was the problem, your fuel economy would be up teh poopoo all the time, and it would "hunt" at idle too.

[GorGasm]

Yeah i think mine does the same. At certain throttle points it sounds as if the A/C switches off.

[bluesky4me]

I know modern cars like the stagea can handle a lot but I am always methodical about when I turn the air con on/off. Like any machine it will work better doing one thing at a time. I always let the car start and idle for a while before puttng on the air con or lights..or in fact anything..I see other people do things like leaving the air con on and just switching the car off with the air con still on..so it will restart with the aircon on...I may be pedantic but I alway think its better to start the car with nothing else on and stop it in the same way. I also return my car to normal auto trans mode before I drive in my house if I have been in triptronic mode..

[pixel8r]

I know modern cars like the stagea can handle a lot but I am always methodical about when I turn the air con on/off. Like any machine it will work better doing one thing at a time. I always let the car start and idle for a while before puttng on the air con or lights..or in fact anything..I see other people do things like leaving the air con on and just switching the car off with the air con still on..so it will restart with the aircon on...I may be pedantic but I alway think its better to start the car with nothing else on and stop it in the same way. I also return my car to normal auto trans mode before I drive in my house if I have been in triptronic mode..

Maybe I should be clearer on this since people dont seem to understand HOW it works...

The only thing that is ON when you start the car with a/c on, is the little LED on the A/C button - that is ALL.

The computer is smart enough that it doesn't actually engage the a/c until the car has been idling for a couple of seconds. Its no different to you pressing the button a couple seconds after the car starts.

To put it another way, its electonically controlled, so you press the button, and it tells the computer that you want a/c so it turns a/c on. When you turn the car off with a/c still on, the next time you start it the computer will remember the setting and light up the LED on the a/c button, just so you can see a/c will be turned on. Then when its ready to turn A/C on, it will, but by this time the starter motor has done its thing and gone back to sleep and the engine is already happily idling away...

Have a listen next time you start the car with the a/c button on, you will hear the a/c cut in a couple seconds after the car starts, ie. not straight away. If its good enough for Nissan, its good enough for me

Gone are the days of manual switches that directly control things.

[rb26stagea]

"You mean he has a machine that BREATHES for him too?! And here I am, using my lungs like a sucker!..." -Homer Simpson

[webng]

I've definitely noticed the car is less responsive with the a/c on. Haven't notice the a/c switching off when i floor it though.

It definitely knows not to turn the a/c on when starting as it is a few secs before the a/c turns on after starting the car. but i still turn it off before switching off and make sure is off when warming up the car. But i'm old school like that..!

[pixel8r]

For the record I reckon my a/c sucks up at least 30 or 40kw (maybe more), not just 10.

I presume it greatly affects torque, and therefore revs up slower, meaning the feeling of lag is increased.

The temperature outside also makes a big difference. A couple weekends ago I drove from home (adelaide) to waikerie, about 2-2.5hrs drive, in near 40deg heat and used half a tank of fuel on the way there, but coming back a few days later at night, (about 30deg) it only used a quarter of a tank to do the same distance.

I think it just doesn't like the extreme heat and also I think I was driving into the wind on the way there...

I dont think my performance does change depending on when i turn a/c on, so maybe i was imagining that. I think its just different day, different result. Cars are like that I guess.

[RS4StagMan]

Check this out.....

" JAYCAR Car Air Conditioner Controller Kit

CAT. NO. KC5437

This kit stops the air conditioner in your car from taking engine power when accelerating such as when you're overtaking or going up a hill. It automatically switches the air conditioner's compressor off when the engine is at a high throttle setting and will allow the compressor to run with low throttle even when the cabin temperature setting has been reached. It also automatically switches the compressor off at idle. When the throttle position is normal the compressor will operate normally. The kit features an override switch, an LED function indicator and is supplied with PCB with overlay and all electronic components."

Don't know how well it would work though......

www.jaycar.com.au