Pontiac Repair: Pontiac 05 Bonneville sle 3.8 loaded, grasping at straws, dash area

Question
QUESTION: Wife's ride with good ears now hears clicking when starting to acellerate. I drove it today and hear what sounds like a small piston opening and closing with a clicking sound. appears to be in center of engine on firewall. She is afraid the pedal may stick and acellerate or just break down. purchased June with 46k, took trip out west, ran greatttt,29.5mpg for 4000 miles, now uses for commute 70 miles per day.
went back to 1999 Bonne with 250000 miles 26mpg. what is the noise?

ANSWER: Good question.. Is the a/c on or the hvac on deforst? It could be comming from the a/c system. If the system is low on a charge. If that is the case the compressor will make noise and then you will hear it in the dash area. If not from the a/c on do you hear it with just the engine running in park and running at idle speed or  do you have to drive it to hear it.. Is ther anyone way to discribe the noise? obvioulsy with out hearing it it's just a guess as to what it could possably be.



---------- FOLLOW-UP ----------

QUESTION: Wow,10am and a response. Air turned off. sat in driveway 1st time in neutral, all quiet, put in drive and just touched gas to move forward. sounded at first like electrical switch left center of dash. 2nd day sounded like small sevo motor when pedal pushed slightly.like piston going forward and back.
does this help?  Jim

Answer
No it really doesn't help much Like I said With out actaully hearing it it's hard to say. I was sure you were going to say it only did it with the a/c on.. does it do it in reverse as well? possably an exhaut leak at the manifold and when the engine is torques in 1 direction it leaks but not the other... I'm grasping at straws here sorry.. There are so may relays behind the dash cluster it could be anything It could be comming out of the speedo cluster and on and on .....