Should under dash on firwall near blower motor.
The blower control module is defective.
Something called a blower control module takes the place and is found in the hole where you would find a blower resistor, so there isn't a blower resistor in that vehicle. As far as the blower control module is concerned, the module is serviced as a unit. No part can be fixed or replaced. This is not to be confused with the control head in the dash. The blower control module is held into the heater box with two 8mm screws outside the firewall under the hood, where you would normally find the blower resistor pack.
1991-1993 DeVille blower control module (power module) location If you are standing in front of the car with the hood open, look left of center on the firewall for a cover that says "Maxi Fuse / Relay Center" remove this cover (two 1/4 turn fasteners on the front and one sheet metal wingnut on the top near the hood hinge). Underneath the fuse and relay center, you should be able to see the blower control module (power module) bolted to the top of the evaporator / blower module. Wires to the connector are color coded; Black, Purple, white and red. Cadillac Man
Open hood . Disconnect blower module located near blower fan. Disconnect, if blower shuts off, repalce module
i think what you are refering to is a blower staying on all the time, if so the blower motor has shorted the control module, you need to replace the blower motor and control module.
Under the hood, not far from the R/S hood hinge it's called a blower module
most likely a defective blower module under the hood
Behind glove-box, behind engine control module
behind the rear seat
The blower control module is located behind the icm module which is mounted to a bracket directly behind the glove box. The blower control module is mounted to the right side of the upper part of the blower housing. It actually seals the upper housing of the blower assembly. When removed you can see part of the fan wheel through the opening. Two 5.5mm socket size screws hold it in place to seal the upper housing. Remove only one and just loosen the other and it removes easily. You must have the connector to the blower itself disconnected to fully remove and replace. Its quite a bit of work to get to but if you have the paitence, it beats paying the mech/dealer mech to do it. Hope this helps.
behind the engine, next to the brake booster, a ring of 7mm screws finess it out wriggling it a little. replace the control module at the same time!!
on the blower module located on the A/C evaporator case R/S under the hood