Surging while air conditioning is running

[Tom92TY]

My Typhoon seems to "surge" a lot when the air conditioning is running. It almost feels like the trans is slipping, but when the air is turned back off, it drives normally. Also, when the air is on, it is difficult to get it to run well from an idle. It seems very hard to get it up to traffic speed unless I get it into the boost a bit.

Is this normal or is it a sign of something bigger to come?

 

[psmvchaser]

a/c

a/c

Mine does the same thing....I have no idea why. Please let me know if you find out.

Ken

 

[SuperStockChamp03]

I have been doing a lot of tuneing at idle and at part throttle lately, and the first thing the comes to mind is that the block learn multiplier is going low at idle with the ac on and causing a lean condition when you step on it. I think this would only cause a stumble and not a long term loss of power.
As the a/c cycles the truck will surge a little.
What are your BLM at idle with the a/c on & off?

 

[Flyin Ryan]

Weird, My truck does the same thing except when I don't have the ac on... My truck idles and drive alot better with the ac on... :roll:

 

[truckins10]

I have simular problems, but I believe theres a wire that runs from the ac switch to the ecm. When the ecm sees the switch turn on requesting ac, it compensates for the load of the compressor by incressing RPM and adding fuel, if I remember right. So you might want to get a wiring diagram and check it out, I still havent done this yet. Let me know Fern Sy#477

 

[warmpancakes]

its called iac forward feed, it bumps the idle up to compensate for the increased load on the motor

 

[Tydriver]

its called iac forward feed, it bumps the idle up to compensate for the increased load on the motor

So with that said, I'd consider changing or cleaning yer existing IAC motor. If you cant recall the last time it was changed or if you know its NEVER been changed it may NOT be a bad idea. A slow, sluggish IAC motor would cause the above mentioned issues singlehandedly.

 

[Fred Aldrich]

Another possibility. Leak/disconnected A/C vacuum hose(s) under the dash. Vacuum is switched by HVAC control so leak is only active in one mode.

 

[philbuilt65]

my truck idled funny 400rpm fluctuation i changed the alternator and cured it but it still takes a lot of throttle to move in traffic need a solution phil k

 

[0-60N4]

Anoterh possibilitiy is the A/C being low on Freon. That will cause the compressor to cycle on and off and the feedback to the ECM will cause the motor to surge up and down.

 

[syclonefrankie]

i had that same problem and it turned out to be a vacuum leak, the stress from the ac drags the motor down and the vacuum cant make up for the drain. put the car in gear, brake down, ac on, and spray ether/starting fluid around the motor in very small bursts looking at vacuum lines and connections. also check that wire under the carpet on the passenger side.
DONT EVER MESS WITH STARTING FLUID AROUND THE MOTOR WITHOUT AN EXTINGUISHER NEAR. just a reminder...not like your dumb or anything.