Help! Truck wont idle w/AC on

[tschwab]

I am down in Petaluma, CA at the KOA campground, site # 171 on an RV vacation, and have encountered a problem, where my truck will not idle with the AC on while in gear?? I thought I might have had a loose line (air leak) so I tightened all lines, same problem, I also thought I might have encountered a bad batch of fuel, so I changed my fuel filter, same problem.



I am now thinking it might be a (TPS) throttle position sensor?



The truck seems to run fine, with the AC off, it idles around 850 rpm while in neutral and about 650-700 while in gear, when I turn on the AC, it drops to about 500-550 rpm and usually dies.



Any suggestions anyone has on what the problem may be or what to do to solve it would be greatly appreciated. Am I at risk of failure on my return trip home? The truck seems to run fine, other than dying while stopped and in gear with the AC on. While running on the freeway with the AC on, there is no problem.



Thanks, and I will check back here in a few days, we just got here and am borrowing a computer to post on the board, we leave to return to WA state, next Saturday AM.

 

[Joe G.]

Idle in gear with the AC on should be 700 at least. It will die at 550 everytime.

 

[Missouri Mule]

tschwab,

I believe what Joe is trying to say is you need to raise your idle speed. Manual states that idle speed on Automatic should be 750 to 800 in drive with A/C on.

You have to ajdust idle with low idle adusting screw.



Looked at A/C section and fuel system for diesels (electronics).

Apparently typo in diesel section as it states there is a IAC= Idle Air Control which will increase idle when A/C is turned on. Gas engines yes they have throttle body.

I was looking for non-electronic componentto raise idle when A/C was turned on. They used to use vacuum before vehicles went electronic.

Haven't found anything like that so adjusting idle speed looks like the only thing you can do.

 

[illflem]

Both Joe and Bill have correctly diagnosed your problem. I don't know why but it seems like many times the idle speed will change on it's own, it's happened to me twice.

 

[CPH]

I had the exact same problem. I was not towing for a while and my idle speed dropped to about 600rpm in gear with ac on. I towed my rv to N. C. I was following my brother since he had the directions. Well, I ended up on a dead end road. While turining around the truck kept dying. Adjusted the idle up to 900 (approx) using the truck tach and a 10mm wrench. All is well. At the end of the summer towing season I may drop the idle to save fuel.



Charlie

 

[azgearpro]

dtt

I have the same problem, I think it might have somthing to do with dtt torque convertor. When you engage from park to drive do you notice your truck wants to take off. because the torque convertor is so tight, the trany drags down your idle, plus the gov spring kit probably adds to this.

The problem i have is I have to set my idle at 950 in park in order to get a suficiant idle in drive with the ac on. with 950 when you go from park to drive it bangs hard.