RPM's jump when AC is on

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Old 04-23-2012 | 11:36 AM
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RPM's jump when AC is on

so i turn my ac on and i see my rpms start jumping when my car is at idle. i know that i have one ripped tranny mount which i will be replacing. but i just replaced all my motor mounts recently. anyways the rpms go from about 800 to 500 and the car feels as if its going to stall out, then it jumps back up to 800 and hovers there for a bit. this happens only a few times when just sitting at idle. i noticed this when i warm up my car every morning and when i was sitting in a parking lot for about 10 min waiting for someone. could this be a need for valve adjustment? or something more complex? thanks for your help!

btw 05 tl 5AT with 68k miles
Old 04-23-2012 | 11:52 AM
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I dont know if the 3G has this but after a quick research the 2G has an idle air control valve that is supposed to modulate the idle under specific loads like A/C.
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Old 04-24-2012 | 06:46 AM
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Check the coolant level while the engine is stone cold in the morning, it may be low & that can cause it until engine heats up.
Old 04-24-2012 | 08:15 AM
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It's probably because of the extra load due to the compressor kicking in. FYI - When you have the A/C on, the compressor cycles on and off.
Old 04-24-2012 | 06:23 PM
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Originally Posted by johnny3
Check the coolant level while the engine is stone cold in the morning, it may be low & that can cause it until engine heats up.
my reservoir tank is filled to the max with coolant so im not sure if it may be that
Old 04-24-2012 | 06:26 PM
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Originally Posted by cbptls
It's probably because of the extra load due to the compressor kicking in. FYI - When you have the A/C on, the compressor cycles on and off.
i was thinking that too because even when i roll up my windows, i feel an extra load on my engine, however i did not experience this in the past, therefore i am confused on what it could be. it recently that the rpms jump that high and low. it settles out eventually but then theres a rumbling and vibrating from the car. in the past when i turned it on, i heard the compressor kick in but the rpms did not change and the car did not vibrate.
Old 04-24-2012 | 07:23 PM
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i had that same issue took it to dealer they did a valve adjustment an it went away
Old 04-24-2012 | 10:39 PM
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Originally Posted by primus
i had that same issue took it to dealer they did a valve adjustment an it went away
ya ive heard about the whole valve adjustment thing? should it happen this early? i mean i only have 70k. and how expensive is it? and does it help out with performance a bit? because my cars been sluggish lately
Old 04-24-2012 | 10:47 PM
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I have the same problem.
I wonder if I just have to do the idle relearn.
Old 04-24-2012 | 11:02 PM
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^^^ by idle relearn, are you talking about unhooking the battery which resets the ecu?
Old 04-25-2012 | 08:58 AM
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Ya thats the first step, but then yoy have to do something else. That way your car idles right, cause if reset the ecu and dont do the idle relearn procedure then your car will idle funny.
Old 04-25-2012 | 11:22 AM
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so just basically unplug, let it sit for a bit and then when you replug it it and turn the car on, should i just let it sit for like 10 min running so it re learns?
Old 04-25-2012 | 11:27 AM
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https://acurazine.com/forums/showthr...t=idle+relearn

search does work sometimes
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Old 04-25-2012 | 11:28 AM
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^^ haha sorry im in class right now
Old 04-25-2012 | 11:31 AM
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Originally Posted by KN_TL
what is step #2? can you please elaborate? thanks
Old 04-25-2012 | 11:35 AM
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Originally Posted by Royik1157
what is step #2? can you please elaborate? thanks
That's where disconnecting the battery should be done.

Originally Posted by Royik1157
^^ haha sorry im in class right now
Just yanking your chain ....shouldn't you be paying attention now!
Old 04-25-2012 | 07:05 PM
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Just yanking your chain ....shouldn't you be paying attention now![/QUOTE]

you are right haha but this class is too boring so i have to keep myself entertained somehow
Old 04-25-2012 | 07:37 PM
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Lol iwas in class too when I was checking this thread out.
I need to do the relearn ASAP, my car runs like junk when my A/C is on.
Old 04-25-2012 | 10:25 PM
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Originally Posted by mY sLOW UA6
Lol iwas in class too when I was checking this thread out.
I need to do the relearn ASAP, my car runs like junk when my A/C is on.
ya man same trying to do it tomorrow. lets hope that helps and its not a valve adjustment problem or something else
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