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air conditioner shaking?

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stealth13

10+ Year Contributor
136
0
Oct 10, 2008
calgary, Alberta_Canada
When I'm driving or sitting and turn on the a/c the whole car starts to shake. Why would this be?
 
Well here's the thing, if im idling and turn on the a/c the rpm drops from 800 to 3 or 400
 
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
 
One of the belts screches pretty loud when I first turn it on when it's been sitting.
 
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.
 
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
 
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?
 
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.
 
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
 
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.
 

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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
 
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 :D
 
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 >.<
 
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