I can't find my block heater cord to plug in my 2005 Equinox inside the hood.  Where is it hiding?

Hiya
The factory install block heater wire harness around the air filter unit area (IF it's equipped with this block heater feature)
IF it's the wire you're searching for to plug it into the electric outlet, here's how to...
Pop open the hood as you stand in front to raise the hood, look for the black square-shaped air filter unit at the left-front side just behind the passenger side headlight area.
There's a black plastic clamp that holds the block heater wire harness onto the air filter's bolt bracket by the front strut tower area (bolt is north of the air filter unit)
That's the route for this block heater wire harness to go around the left side of the air filter unit.
In case you do locate the block heater wire harness there, follow the wire harness route until you find the plug socket.
Perhaps it's underneath the air filter unit or tucked somewhere behind the headlight frame area.

The heater core is not under hood it is locatied behind glove box inside