Hesitation while running A/C...

[wcialrlter]

I'm new to the 6.5's, so bear with me...

2000 3500 Van with 6.5 and autotrans

When running the A/C it likes to hesitate throughout rpm range. Only does it when running the air conditioning and I can't feel any sign of it when it's off.

Just changed the fuel filter and tested lift pump pressure at the the water drain-off port. Even with a little fuel leaking (just a drop here and there) it still showed slightly over 3psi.

Just want to make sure there's not something obvious wrong before I go through the normal routine of checking things...

Any thoughts?

[rhsub]

This hesitation your feeling sounds like it may be the A/C compressor turning off and on
check this by manually turning a/c on and off and see if feeling is the same, if so your A/C is likley low on refrigerant. Is it blowing cold air (40 to 45' F) A/C on max, fan on low, engine on high idle 1000+ rpm, at centre dash vent
is compressor cycling on and off a lot
Let us know
Ron

[wcialrlter]

I can feel the pump kick on...it actually seems quite drastic...it'll slow down pretty good...I've never had one have that much of an effect on a motor.

This hesitation can be felt pretty consistantly when pulling a hill but as soon as you turn off the A/C it seems to run great.

Also at 60mph or so it likes to buck, in and out of fuel almost, but again, only when the A/C is on.

[mobilevet]

How are your volts? I recently had mine start throwing codes (and maybe once actually have a change in performance) when I turned on my front and rear A/C together with the fan going. My voltmeter was dropping to down 12v. Turned out I had some bad grounds, in adequate line running to the hot post on the firewall, and both batteries had bad cells. Simple check is that you should get 13.25 or greater volts at the firewall hot post with all the loads (lights, A/C's, fans, blinkers, etc) on while at an idle - anything less means you need to look into the power supply....