air conditioner shaking?

[stealth13]

When I'm driving or sitting and turn on the a/c the whole car starts to shake. Why would this be?

[mirage_david]

Have you removed the belt and spun the pully by hand? The bearings could be bad.

[miguelmcv]

How hard it shakes?.

My car used to do the same thing, But it was light shake.

The problem was my AC Fan, It was vibrating when turn on.

Replace the Fan and problem solved.

[stealth13]

Well here's the thing, if im idling and turn on the a/c the rpm drops from 800 to 3 or 400

[miguelmcv]

Are you Idling at all?.
If you have a bad Idling, It can be a leak.
Also check your ICS. It can starting to go off.

[stealth13]

Originally Posted by miguelmcv

Are you Idling at all?.
If you have a bad Idling, It can be a leak.
Also check your ICS. It can starting to go off.

it idles great when the a/c isnt on

[miguelmcv]

Check your ICS and check your TPS as well.
But My bet goes to the ICS.

[SeaveeDSM]

Originally Posted by miguelmcv

Check your ICS and check your TPS as well.
But My bet goes to the ICS.

I think you mean ISC, not ICS.

[miguelmcv]

Originally Posted by SeaveeDSM

I think you mean ISC, not ICS.

By Bad.

(ISC).

Thanks to clarify.

[Spades]

Try unplugging the AC compressor relay and turn on the AC, the compressor wont turn on but the idle should rise to about 1300, if it doesnt then either the ISC isnt compensating or check for +12V at pin 45 at the ECU

[blackGSX2g]

Originally Posted by stealth13

Well here's the thing, if im idling and turn on the a/c the rpm drops from 800 to 3 or 400

Sounds like you need to test your IAC coils and properly set your idle.

1G BISS Adjustment

[stealth13]

My car is a 2g, is that the same?

[Mackadoches]

Sounds like the a/c fan to me. Unless your rpm's are jumping erratically then I would think it has something to do with you ISC. Thats my educated guess. Does the belt screech?

[stealth13]

One of the belts screches pretty loud when I first turn it on when it's been sitting.

[Mackadoches]

Originally Posted by stealth13

One of the belts screches pretty loud when I first turn it on when it's been sitting.

Yep a buddy of mine had this same problem. Although his car didn't shake like yours. The screeching was coming from his a/c belt. Which if thats the case for you, it narrows your point of issue down to your a/c unit/fan. I would think that is where your shaking issue is originating.

[eeeric16]

I have this same problem - its not the a/c fan. When i push the a/c button the whole car starts shuddering and rocking. And the idle drops much lower you can feel it working harder. I know its not the a/c fan because i just installed new slim fans and it still does it

I was thinking it has something to do with low refrigerant in the compressor or something of that nature. Haven't really checked into it yet

[Mackadoches]

Originally Posted by eeeric16

I have this same problem - its not the a/c fan. When i push the a/c button the whole car starts shuddering and rocking. And the idle drops much lower you can feel it working harder. I know its not the a/c fan because i just installed new slim fans and it still does it

I was thinking it has something to do with low refrigerant in the compressor or something of that nature. Haven't really checked into it yet

This sounds like an altenator problem. My wifes car used to do this when she turned her headlights on. Have you had your altenator checked?

[eeeric16]

Originally Posted by Mackadoches

This sounds like an altenator problem. My wifes car used to do this when she turned her headlights on. Have you had your altenator checked?

yes alternator checked out good. Haven't had any other problems related to the altenator. It only acts up when you push the a/c button and turn the fan on, but when i manually tested the fans to the battery they ran smoothly. I'm actually going to take a short video of what it does tomorrow and post it on this thread so you can see exactly.

[stealth13]

Ya that sounds like mine, the rpm just drops from 800 , I can have lights and stereo cranked with 2 subs no problems, but the a/c... I dunno

[johnovision27]

Originally Posted by stealth13

Ya that sounds like mine, the rpm just drops from 800 , I can have lights and stereo cranked with 2 subs no problems, but the a/c... I dunno

The reason your RPMs drop with the AC on isn't because of the stereo, headlights, or disco ball in your car, it's because of the increased load on the engine.

As previously mentioned, check your ISC. When you turn your AC on, the ISC compensated for the increased load by opening up a little thus allowing more air in, and the RPMs should rise a little. (unless you've done some idle air nonsense to change that...) If they're dropping, I'm willing to bet your BISS is out of wack, or your ISC is toast.

To test the ISC, you want to disconnect the plug, get a DMM (digital multi-meter) and measure the resistance between pins 1-2, 2-3, 4-5, 5-6.
Someone might need to correct me here, but I believe you should get a reading between 28 - 32ohms. Higher is ok, lower.... well, I guess we'll see.
If you don't get any reading, or there is no connectivity between one of those 4 connections, your ISC is toast.

[eeeric16]

And just to clarify, what is ISC? :P I'm going to set my base idle speed back up to 750 tomorrow. I'm looking in my haynes manual and not seeing anything for ISC

Scratch that, i was looking under cooling and a/c. found it in fuel and exhaust

[johnovision27]

There ya go. haha. It's the controller on the rear lower corner of the throttle body. (pretty sure thats consistent through all years)

Make sure you have the tools to set base idle (DSMlink ideally) Don't just go twisting and turning your BISS. If you set that incorrectly, then you're on the right path to burning the ISC out, and they aren't that cheap. Looking around $150 for a used one, unless you get lucky at the wreckers

[eeeric16]

yep thanks john for the info very helpful I'll check both that and reset my idle speed tomorrow

[johnovision27]

No worries and good luck with that AC. We need it during this heat wave!

[eeeric16]

okay i reset the idle to 750, and then i checked the isc with an ohms meter. it read 1.1 from 1-2, no reading from 2/3 or 3/4, 1.1 from 4-5, and nothing from 5/6. I'm going to assume i need a new one to fix this.

Also, after i reset the idle my car won't start. It has enough volts to start, the starter is engaging but it won't turn over >.<

[johnovision27]

You got it. ISC is toast. Check dsmgraveyard.com, a local wrecker, the classifieds, etc.
How did you reset the idle?

[eeeric16]

i followed the guide that blackgst posted up there ^^
and i have a spare engine (except its a turbo '93 front wheel drive) but i think that part should be the same if I'm not mistaken. Next time i get a chance I'll try and swap them.

[stealth13]

Mine seems to have fixed itself... Just driving with it on it eventually just learned to raise the rpm's.

[johnovision27]

Should be the same part. Just test it before you put it in.