Phaedra, this chirp sound could be your alternator or water pump belt.
Try a little (really very little) spray on belt dressing and hear if the
sound changes. It could also be a bearing on either the alternator or
water pump. In this case the chirp will not change with the belt
dressing. You need to have the belt tension changed on first one then
the other belt and hear if there is any change in the chirp.
IMHO The mechanic should do it. It was probably caused as a result of
your recent tune up anyway.
-Larry

PSavage wrote:

> I can see I did not offer enough good clues re
> this new sound in my van since it returned from the shop.
> Here's the best I can do:
> Sound seems to be coming from the rear.
> I have only heard the chirping when I am driving
> & have not listened from the rear of the van.
> Chirping seems to increase in speed with engine speed.
> Van was just tuned up, among other things...
> Front & rear brakes were done along with rotors.
> Any ideas?
> Phaedra