Fluctuating Idle-Rpm when AC on....

[MYVW]

Just started to happen. Car idles perfectly, however when I engae the AC the idle rpm fluctuate. Seems to be ok once the car is completly warmed. Had chck enging light come on once...the obd code said intermittent throttle body failure. Reset the obd and haven't had the light come on again. Car runs perfectly, smooth, good power etc...just this crazy fluctuationw when AC is on, mainly when car is not fully warmed.

Advice greatly appreciated, I really don't want to throw money at a new throttle body
especially with nthe car running so smoothly.

...Bob

[Just_J]

Check for loose cables/hoses. I had a similar problem and noticed one of the hoses connected to the air intake hose was off.

[golfzex]

Yeah, check all your Vac hoses. Also you can take off your TB and clean it with carb cleaner.

[MYVW]

Originally Posted by golfzex

Yeah, check all your Vac hoses. Also you can take off your TB and clean it with carb cleaner.

Thanks for the comments. There are no leaks, no hoses disconnected, TB was cleaned as well. Although this is a 98(I'm original owner) the TB was replaced by VW in 2004 so its not all that old. Never the less we did do a cleaning. The car runs perfectly, absoluetly stable idle rpm without the AC on, isue only appears when AC is turned on. I've now noticed the fluctuation(with AC) occurs when the car not fully warmed up. Hard to imagine since we're had 90degree days here. But after driving the car about 5+ minutes it seems to be fine.

Everyone tells me it's the TB, I'm hesitant to spend the bucks without a bit more certainty. My mechanic suggests leaving it alone...wait and see approach.

[BadBradokc]

Check all your sensor connections, Especially the CTS (Coolent Temperature Sensor) it can affect your idle speed. I have had the same prob on several cars, the sensor connections get corroded, or aren't properly attached.