There are a bunch of relays under the hood near the firewall on the passenger's side. One of them might be for the de-fogger but you should call a GM dealer's service center to find out for sure. Also, Amazon or eBay should have Chilton repair manuals dirt cheap.
Do you mean the main switch by the driver or the switch on the door itself?
In most GM vehicles, the turn signal relay can be found to the left of the steering column, under the dashboard.
If it's anything like my 1993 Skylark Custom 3.3L, it's in a bank of relays located toward the top of the firewall inside a protective black box. You may need to trim the mounting tab off a replacement relay to get it to fit in the box.
Skylark - 1993 TV is rated/received certificates of: Canada:PG (Ontario) USA:G
It is located under the hood in the fuse box.
won't idle
I think it's one of those four relay switches right above the blower motor near the firewall. A service center at any GM dealer will be able to tell you for certain.
I found mine high up behind the drivers kick plate. There are 2 relays in that location, the window relay being the top most one. It would be good to have small hand as it is very hard to get to.
you replace it by...hold on
fuse-box under hood
on the steering wheel
It's around 2800 pounds.