Idling problem when a/c compressor goes off...

[wiretap_md]

Here's the situation:

My idle speed without a/c on is set to 850 rpm. As soon as I turn on the a/c or when the a/c compressor engages if the a/c is on already, the idle rpm goes to 1000rpm as compensation. Afterwards, when the a/c compressor automatically switches off kung malamig na or if I turn off the a/c compressor manually, the idle drops to about 500rpm before it slowly rises back to 850. Takes about 4-5 seconds in going back. Parang mamamatay tuloy ang engine and you could feel the vibration na. Well, di naman gaano ka worse na I have to step on the accelerator pedal to prevent the engine from stalling.

I tried increasing my idle speed to about 900 or even 950 pero same pa din ang problem. I asked my mechanic in Bacolod about it and he said to try cleaning the idle speed screw coz sa vitara the idling rpm is adjusted by turning a plastic screw near the throttle body that acts to regulate the amount of airflow. I removed the screw and checked its tip and there were some carbon deposits. CLeaned it and reattached it pero same pa din ang problem.

Someone suggested na baka it could be a vacuum hose problem that connects the a/c compressor to the throttle body. Is this logical?

Btw, I changed my sparkplugs already since malapit na 50K pms ko and hoping that it might have been the source of the problem pero ganun pa din.

All your inputs would be highly appreciated. Thanks!

[jackaroo]

I've seen this happen to a miata, CRV, Civic. I clean the throttle body by removing the plastic intake hose, holding butterfly flap open and spraying some carb cleaner into openning. (Engine will take longer to start if you use too much carb cleaner.)

This cleans out the gunk from throttle body vacuum lines and hoses. You'll see an increase in idling if done right. :wink:

[afrasay]

check your idler-up switch. it's that thing that has a hose and an electrical connection to the a/c compressor. baka hindi nag engage completely. also , check the condition of the vacuum and hose (crack or leaking air). your RPM should stay at 850 whether your aircon is on or off.

[wiretap_md]

Thanks guys. Will check later

[mike_0197]

guys...may be you can give me idea how to solve my problem ....sorry to interupt you guys..... coz my ride GLXI 93 matic having problem about flactuating up and down pag open iyon A/C .......they keep on saying servo ... kasi may be there are other factor kaya nag kakaganon ang idling.... please help me ... thanks

[wildthing]

probably similar situation as doc wiretap's zuk...the servo you mentioned is likely the same idle-up switch (that was mentioned by afrasay)....ang nagtitriger ng switch na ito ay vacuum from the engine ... so if that switch have a problem, magiging fluctuating ang controls ng idling (isn't this what you are observing)....sometimes the switch is okay pero meron air leak ang hose (lumang car will have this common sakit) so fluctuating din ang idling.

This can be done DIY with minimal purchase of parts (vacuum switch/servo na ang medyo mahal) the hose is about P12/ft.

HTH.

[theveed]

Happened several times sa Corolla ko dati bro, usually theres a small leak either on the idle adjustment thing on the firewall or a hose that has a leak.

I doubt that it's something serious.

[H1Tman]

Happened several times sa Corolla ko dati bro, usually theres a small leak either on the idle adjustment thing on the firewall or a hose that has a leak.

I doubt that it's something serious.

sir dave, if that's the problem, should i go to an electrical or aircon shop? tia!

[theveed]

i'd think aircon shop... sakin kasi sa AC shop nahuli eh.