shaking when ac on

[henrytad]

Hey everyone, when I've been driving for about 10 minutes and I turn my ac on, the car starts to get this really unhealhy vibration and shake like its about to turn off and it does in every 5 seconds or so until I turn the aircon off. All I can think of is if its the second fan sstruggling to turn on lr some thing..
Any suggestions before i blow the car up

[RiCeY]

Has the AC compressor siezed up?

[henrytad]

How do i check? The aircon itself still cools perfectly

[Stewlz]

My sv6 did the same, and from time to time at idle it would do its wobble. Since then I've only run 98 through the engine and it hasn't happened at idle for months and not often with a/c on. I had my plugs changed as well later down the track which may have helped. I put it down to a possibility of a few things being: fuel, compressor pulley slipping or shit bearings, plugs or coils, fan problem. But yeh if you don't run 98 maybe give it a go

[henrytad]

I always run 98. Can't stand ethanol shit as it runs out quicker

[SavVYute]

Could be a sticky or blocked IAC valve if it is doing it a idle. Throttle body might need a good cleaning.

[dijm8]

just pretend you have a big lumpy cam under the hood

[Stewlz]

Isn't the idle control done via ecu?

[SavVYute]

Isn't the idle control done via ecu?

Yep. The ECU controls the IAC valve on the throttle body. The IAC then regulates the airflow through a bypass to give the correct RPM at idle.

[henrytad]

ive never actually done a throttle clean. how do u perform it?

[CRUSTIN]

take it off and clean it? Brake cleaner or carby cleaner with a rag.

[SavVYute]

ive never actually done a throttle clean. how do u perform it?

A basic throttle clean is fairly easy
Grab yourself a (spray) can of throttle body cleaner from supercheap / repco etc and an old toothbrush.
Undo the big hose clamp holding the air inlet hose to the t/b, pull hose off and push it to one side.
Put an old towel or rag under the t/b (to catch the carbon gunk you’ll flush out)
Spray the cleaner into the t/b and gently give it a scrub. Manipulate the throttle blade and make sure its nice and clean both sides.
The spray should come with an extension tube you can use to flush out any bypass vents you see or feel inside. One of these is the idle bypass.
Wipe out inside with a clean rag and reattach the big air inlet hose.
That’s it for a basic clean. MAKE SURE YOU DO IT IN A WELL VENTILATED AREA and NO SMOKING.

[henrytad]

ok thanks for that. ill see if i can do it this weekend and post up if it makes a difference.. the onli other info i got is that it could be the second fan trying to start and it might have n issue but ill get my mechanic to check it out

[RiCeY]

Dont spray it into the throttle body, spray it onto a rag then wipe the throttle body and plate clean.

By spraying it in there you risk damaging the electrical components that are part of the throttle body. You may get away without damage but do you want to risk it?

[SavVYute]

By spraying it in there you risk damaging the electrical components that are part of the throttle body. You may get away without damage but do you want to risk it?

The electrical side of the throttle body setup is all outside, isolated from the inside workings. I think it is safe to flush the carbon and grunge from inside using the extended spray tube supplied with the can of cleaner.
But RiCeY's right... go easy if you're cleaning the outside around the throttle position sensor and idle air control valve electrics.

[henrytad]

so to be exact, cause ive never done this. i have to take the main hose the manifold part of the engine and clean insider there?

[Dr.304]

How about a bottle of subaru upper engine cleaner? / Seafoam?

[henrytad]

which is best for me to use?

[greenacc]

It's the chunky black plastic pipe that runs from your air filter box to the front of the intake manifold. Undo the big hose clamp that clamps the pipe to the manifold with a screwdriver and pull the pipe off. Theres a whole new world in there.

[henrytad]

ok cool, ill give that a go this weekend then. so once i take it off i just wipe the inside, not spray?

[RiCeY]

Thats the safest way, spray the rag then wipe all the black crap off.

[henrytad]

ok cool, im gonna do this on the weekend then and ill clean my air filter too and ill post up what happens

[henrytad]

so i did a throttle clean, i was shocked at the amount of greasy stuff there was there. wiped it clean and the aircon hasnt done that shaking since. but i have a new problem hoping you could help. when i turn the car on, it struggles to idle and keeps shaking for about 10 secs and finally shows up check powertrain and idles. have i put the MAF the wrong way.. there is an arrow on it pointing to airflow. i have it installed so the arrow is pointing towards the airfilter. is this correct or should it be the other way around?

[Stewlz]

Other way round bud. The arrow points the airflow as you said, which is through the air filter and towards the throttle body at the front of the intake manifold

[henrytad]

lol i just did it like that and its working again. what a stupid error that was !! i was wondering why my revs were so different n slow as if i was driving a v4