Hey guys,
I am a VP guy but my brother has a 12v and he was at my shop yesterday and he has an issue at idle. When he is sitting with the truck in Park and the A/C off it idles fine. If he turns the A/C on and still in park it idles fine. If he has the truck in Reverse or Drive and the A/C on it will surge. Neutral it will not surge. If you turn the A/C off in Reverse or Drive the surging will stop. There is no miss when driving from what he says and never misses a beat, only when he is sitting still and in gear with a load on the engine (A/C). If he has the truck in Drive, A/C on and it surging and he gooses it the truck will die. I mentioned it could be something with his transmission, Im just not sure what. Do you guys have any Idea?

His Truck
'97 2500 Auto No mods 200,000 miles

Thanks guys!

swordfish

 

Whats the idle at in drive with the A/C on? Does it surge when its moving at idle, or just when the foot is on the brake?

 

Idle should be around 700 in drive with a/c on. I kept mine around 850-900 free idle, and in drive (when it was an auto!) I was around 750, dropped a little below that with a/c on. I had the same symptoms before, when idle was at about 700 in neutral.

 

Thanks for the replies guys. My brother is in Daytona right now so I texted him to see if he knows the answers to your questions. I will post back when he gets back to me.

swordfish

 

I got his response, he said only when the brake is applied. Not while moving under idle.

 

I bet if he kicks the idle up 100 RPMs he will solve his problem.

 

I just wanted to report back. I talked to my brother last night and when he is idling with the AC off and in Park/Neutral he is seeing aroung 650 RPM....I told him to bump it up. Thanks for the advice guys. I appreciate it.

swordfish