On the bottom of the heater/AC housing under the dash.
On the blower housing. Remove the glove box to gain access.
The blower is controlled by the blower switch, blower resistor, and relevant power relay.
There is really no method to "check" the resistor, text by substitution.
Remove the glove box. The front blower motor and the resistor can be accessed from there.
Held in by two small screws under dash.
Under the dash, at the extreme right near the passenger kick panel.
Under the dash on the right side.
the only goofie looking board you will find under there
In the ceiling housing for the rear A/C.
the heater blower resistor is located on the passenger side footwell near the firewall. a complete how-to replace the resistor, along with photos is available on newcougar.org http://www.newcougar.org/forums/how-tos/3732-fixing-heater-blower-resistor-install-photos.html
The blower motor fan cools the resistor so the resistor is usually located close to the blower.
The resistor is located on the duct work under the dash. Sitting in the passenger seat facing forward it is to the left of the blower motor mounted on the duct work firewall.