idle is confused

[doogie78]

when i put the a/c on it idles at around 1000 thendrop down fast to about 200-250 then back up to 1000 again. Like the a/c is switching on and off, but it's not.

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injen cai,b&m shifter,borla exhaust,superchip,ford udp, don't underestimate a sleeper

[ax0n]

That's almost normal.

You compressor doesn't run all the time. It goes on and off a lot, especially at idle. My car idles at about 670-700 normally, and it drops to 400 or when the A/C compressor kicks on if I'm idling. If you pop thwe hood and have your engine and AC running you can hear it if you go over where your alternator is (Accessory Drive Belt) Click-whirwhirwhirwhirwhir-CLICK, every few seconds.

[doogie78]

I understand, but it seems to shut on and off frequently. As soon as the rpm's go up they drop right down then right back up again.

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injen cai,b&m shifter,borla exhaust,superchip,ford udp, don't underestimate a sleeper

[smd3]

I wouldn't call this normal. My Z doesn't idle that low when the A/C is on. In fact I don't recall a noticable fluxuation at all.

On the other hand my A/C doesn't seem to get very cold either...

steve

[JonBoy470]

Sounds like a problem with the idle air control system. The IAC is supposed to regulate the idle of the engine, so that it idles at a constant speed regardless of increased load from the accesories.

To see the system is action in a well running car, start the engine, and with the car idling and stopped, turn the steering wheel right (or left) all the way, without gassing, or moving the car. You'll notice the RPM's dip slightly (as increased fluid pressure makes the power steering pump work harder), then increase back to normal very quickly. That is the IAC in action. It also should compensate for A/C compressor cycling, and water pump and alternator load fluctuations.

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-Jon
2k ZX3, Infra-red, auto, air, cruise, tilt, pw/pl/pm, abs, var. int. wiper conversion, Sylvania XV headlights
IM: JonBoy470

[STEEDA18]

if you disconnect your battery and hook it back up your car will have to re-learn its idle characteristics. i don't know if this will help but there you go.

[Stay Focused]

Typically, how long does it take for the ECU to "learn" its idle characteristics? Mine is currently idling at 1,750 and races to 3G between shifts. [img]graemlins/thumbdown.gif[/img]

[ASUFocusZX3]

it is normal for the A/c compressor to cut on and off, like someone else said, but it should do this to a point. If it is coming on then shutting off not 5 seconds later and keeps doing this go get your freon levels checked, becuase that is a sign that the freon is low, mine did this before and it was low on freon, now that it is right it cuts on and off but will stay on for couple of minutes then shut off and then come back on a couple minutes later. Hope this helps.

[size="1"][ 03-24-2003, 04:05 PM: Message edited by: ASUFocusZX3 ][/size]