AC causing engine surging

[Benzalot]

When my AC is on, the engine surges at idle, anyone know the culprit causing this. AC is off all is fine.

[Logic]

well when the a/c is on it take little more power to run especailly at idol. so unless you need a tune up your idol speed might be a little low

[Nelson Lago]

I'm not sure what year yours is, i have the post-updated model 99c280 so I don't have an IAC and im not sure if pre-updates do but the IAC( Intake Air Control) lets air by-pass the throttle plate to keep the idle at the correct rpm. When the A/C is turned on the IAC moves to let more air pass the throttle plate to maintain idle. You might need a new one or it needs to be cleaned. if you have the post-update we have an electronic throttle plate that will open slightly when under load " when A/C is on" and like the IAC, it might need some cleaning or replaced, but i don't know much about the electronic throttle plate so their could be many outer problems or its normal

[Cru328prod]

i have that problem without the a.c on....i'll drive and come to a stop and it will do that....1 time it did a stall

[mike mac]

when i turn mine on, it obviously robs power, BUT the RPMs just drop!!!! also same when i put on an Electrical load( I.E. lights, Etc)

i do have a new battery
my altinator is good, maybe going. idk

has anyone ALL experianced that?

[Cru328prod]

ok all of this had mad me think its the throttle actuator, yes i know it may sound a bit weird and out of the blue...

but the reason for this, in park its 20psi vac, and when i drop it in drive....it goes to 10psi vac....in reverse..it says at 20psi...very weird...i'll trouble shoot this issue Thursday after i get my motor mounts done....if i can't figure it out......off to extended warranty it goes lmao