2000 Sonoma Engine surging

I have a 2000 GMC Sonoma 4.3 V6. 11/24/2008 Here is my problem; With the Heater/ AC switch on the off position the engine runs as normal. When the heater/AC switch is turned on to any combination of cabin vents the engine surges 300 rpm at an idle or traveling down the road. Even at a stoplight, foot on the brake, it surges 300 rpm over the idle setting. Help please.:crying:

Try cleaning the throttle body and iac for starters, then if no difference, disconnect the ac compressor and see what happens.

What is the IAC, please????

Idle air control.

Thanx Max

Max
I disconnected the compressor and the surging went away. With no garage to clean the parts you suggested. Am I able to leave it disconnected through the winter?

Yes, but the compressor works with the defroster at temps above 40 for help defog the w/s. This assumes your works properly.

Okay now I’m stumped. The compressor is disconnected. Now the engine wants to idle at 2000rpm while in drive or park. Sometimes when not using the heater(off position) the engine runs as it should. Most of the time it idles way to high. Even while driving. Makes coming to a stop on snow covered roads interesting. Almost took out a neighbors garage door. The check engine light is not coming on. So I assume there are no codes to check. We are experiencing a very cold icy winter here in Ohio. Driving is an experience without the truck idling too high.
Any ideas?:uhoh:

vette,does the surging get worse as the truck gets warm?
does it seem to lack power also?
the platinum in my cat melted..living barly any airfllow,so i gutted it out. and now it runs like a champ.
and also the the butterfly in my cold air intake was stuck shut.
i dont no if we share the same problems or not but,thats my reply

Dave

vette,does the surging get worse as the truck gets warm?
does it seem to lack power also?
the platinum in my cat melted..living barly any airfllow,so i gutted it out. and now it runs like a champ.
and also the the butterfly in my cold air intake was stuck shut.
i dont no if we share the same problems or not but,thats my reply

Dave


Tampering with the emission control system is against the law, even if it's your own vehicle! It carries a fine of $3500 by the US EPA, and possible jail time also, no questions asked! It's probably not a good idea to call attention to the fact that YOU did it! Please don't offer illegal advice to other members on the forum.