OK,

When I bought the truck the previous owner said that when you charge put freon in it just comes out the back of the compressor. I thought duh the high pressure valve. So I put a new one in, added some freon, and todah!!!! Cold Air. This was all fine and great until two days ago when I pulled a trailer for the first time while running the A/C. I thought I was going to have to get out and push. I finally started turning it to vent when I started off because it would pull the truck down so far. It didn't seem to affect it at cruising speed. So what should I look at doing? The truck is completely stock except I cut the factory muffler off and added a piece of 3" straight pipe in its place. Will a 3200 spring give me enough increased RPM's that I won't lug the truck so much when shifting. BHAF? I saw some stock 215hp injectors for sale from a 97 12V. Would they help? I know the valves probably need set, but I'm not sure how much this will help the performance. Can I adjust the pump (Star and Smoke) without upping the fuel until I can get a set of gauges? My truck never smokes. Even at WOT from a dead stop. Rotate the fuel pin? Any ideas would be greatly appreciated.

 

I assume your not towing to heavy. That Cummins shouldn't even know the compressor is running. Easiest thing first would be fuel supply. A clogged filter could cause the problem since you need the most fuel to accelerate with a loaded trailer. I would check the lift pump also. Next I would check the boost. I am no expert, but a Cummins that won't pull isn't going to benefit much from higher rpm and more fuel. Of course new injectors might help but I think your problem is a lot simpler than that.

 

Mine has no problem with A/C on MAX, fan-clutch pinned to direct-drive, 9800 pound truck, big gooseneck stock trailer, and cram-full of big Charolais cows.

Up hill and down, stop-and-go or highway speeds, the only thing that will cause me to back out of it and gear down is the climbing pyrometer.

If you are having trouble pulling the A/C, you have some kind of fuel restriction, collapsed exhaust, frozen turbo bearing, or something going on.


Plumb in a fuel-pressure gauge and see what it holds; as, your VE may be having to draw it's own fuel.

 

The first thing I would do would be to check the AFC diaphragm and see if it has any tears in it also at this time you could set it at it's deepest side.
If the diaphragm is not holding pressure against your boost in stock form the truck could be gutless.
Also see if your air conditioner is not overcharged.
The 3200 spring will make it a lot more drivable.
Jim