1994 2.3 Idle issues with AC on.

[jfkansas]

I thought I read something about this here but can't find it. When I have the AC on and come to a stop the engine will idle very low and almost die. I haven't replaced anything related to this. Would this be related to an IAC valve or Throttle position sensor? Or is there another device that controls idle for the AC?

 

[Earl43P]

Most likely an IAC issue.

Clean it and replace it if cleaning doesn't help.

I typically use carb/choke cleaner and a brush to get the stuff off the shaft. I also use a small blade to move the actuator along that shaft.

It may help to reset the computer after the cleaning so it will relearn its idle (disconnect battery, turn on/off lights, reconnect battery.

 

[killj0y]

x2 on the IAC valve, just clean it really well. Although i would only recommend a quick drying no residue cleaner like electric parts cleaner or brake cleaner. While your at it you can clean your MAF and all those sensors too. Anyways you can get that stuff from any auto parts store for a few bucks a can.

 

[jfkansas]

Gotta love 3 dollar fixes, is this a temporary fix? The resistance between the poles of the motor measured good.

 

[killj0y]

I've cleaned several on different brands and models, I personally have never had to replace one, a good cleaning does wonders. At least on our models they are easy to get too lol. On my wife's BMW i had to just about take apart the engine to get to it lol and the part was 300+ dollars to replace so it was worth the effort lol.

 

[disciplerocks]

If it was the IAC, it would more than likely be surging at idle. Sounds like a vacuum leak to me.

 

[killj0y]

Actually I have had both my ranger and the old lady's bimmer both do the low idle and die thing, not only that they would bog down and would not want to travel faster than 5 miles per hour at take off for a good minute or so. Cleaning the IAC valve on both fixed the problem. If it only does this with the ac on it obviously the strain the ac is putting on the engine, as i understand it the IAC valve counteracts that by raising the idle so the vehicle stays on, but if it is stuck it stands to reason that the valve does nothing or very little in regards to adjusting the idle. In any case it will take like 10 minutes to remove and clean and cost like 5 bucks for the cleaning agent, so its the easiest place to start and if not at least you can eliminate it for now.

 

[killj0y]

I could very well be a vacuum leak as well but I hate hunting down vacuum leaks lol.

 

[seth556]

Replaced the evaporator core yesterday and got the ac system filled with refregrant today. The mechanic said the compressor was pretty weak and so that's why at idle it is very rough just as you described while at higher rpms it runs fine and the AC works fine. Just an idea.

 

[v8318cid]

Weak A/C compressor = lower operating pressure, thus less strain on the engine. Not a likely cause of rough idle. Erratic maybe due to constant on/off cycling. Unless you mean the compressor was underpowered rather than worn out. IMHO anyway.

 

[seth556]

Underpowered maybe? It's usually when the engine is colder that it idles the worse. It's not too bad except for when it's on "max ac" it cycles on and off pretty often.