Window regulators are always inside the door.

This site is pretty good for having pictorial displays
for fixing the Elantra.
http://www.elantraclub.com/forum/index.php?act=home

Motor problems are much more frequent than regulator problems on 2001-2006
Elantras.

------------- ME, TOO, TROUBLE WITH THE HYUNDAI WINDOWS, AND MUCH MORE
----------

TAKE THE BATTERY -- PLEASE!  THEY'RE almost impossible to replace and
service!

Hyundai DOESN'T want you even try to:

1)   Check the fluid level in the battery cells.

2)   Check the body and terminals for corrosion.

3)   Remove the old battery and install a new one.

These tasks are almost impossible for the average motorist BECAUSE THE
BATTERY SITS IN AN ENCLOSED, SEALED CASE!   You can't see much less
inspect the cell fluid levels.  And half of the bolts under the hood
on the driver's side have to be removed to free-up the battery.

See, Hyundai wants you to go to a HYUNDAI DEALER, where a battery
costs $90, plus up to $50 more to install it. And at most Hyundai
dealers I know, you have to leave your car for an entire day -- then
hope it's ready when you return in the late afternoon or early
evening.

"Aw, we're sorry, but you see we got real busy and couldn't get to
yours.  But tomorrow!"

AdvanceAuto Parts, AutoZone, Olympic Auto Parts, and Batteries Plus
sell the same battery for $52 to $69, some including free
installation.

Only problem?  They can't get a sufficient supply of them to keep 'em
in stock!

And that's what your conniving, inscrutable Hyundai folks want -- to
force you to spend more on a new battery than a normal car owner would
expect.  Parts companies list the Elantra batteries as "special."  And
that they are!

Additionally, the OWNER'S MANUAL has neither a diagram or instructions
for accessing and servicing your Hyundai Elantra battery.  Just a one-
paragraph entry that says, in effect, Be careful when servicing the
battery."

I've had my 2004 Elantra GLS for 3 years and the battery is already
shot.  Needless to say, with problems also with the air bags, brakes,
power locks, and engine noise and vibration, I've bought my last
Hyundai product!

My advice to Hyundai?  Hold up on building those factories in the
U.S.  Too many one-time customers could make for sluggish, then
anemic, sales.

----------------------