The most likely problem with the heater blower on your 2003 Sable is the blower resister. The resister can go bad and cause you to only have one speed.
No one knows if:The heater is NOT blowing - or blowing on high speed only, or... The heater IS blowing, but the air is NOT hotEither way, the "Related Questions" below will get you started
NO!This is a great do-it-yourself repair!Other than some cars having a bit of trim piece over the passenger side, blower motors are just 3, maybe 4 small screws and 1 electrical connector.Sidebar: the blower resistor that provides the ability to have more than one blower speed, is just to the left of the blower. An even easier repair, and not uncommon to fail (blows on high speed only).See "Related Questions" below for more
You probably have water tht has entered the heater case through the cowl air inlet, which has damaged the heater blower resister assembly. It is held into the case with two 8mm screws, and is locatted under the glove box area right beside the heater blower motor. Turn on the blower and follow the sound, and you will find the resister assembly right there. I'll bet if you replace the resister assembly, you will have all your speeds back again.
On the transmission.
The blower motor speed resistor is burned out.
Blown fuse. Burned out blower speed resistor. Faulty blower switch. Bad blower motor.
In general the heater blower motor speed resistor is located in close proximity to the blower motor.
The blower motor speed resistor is burned out. The high speed function bypasses the resistor. The speed resistor is generally located near to the blower motor.
heater blower resistor has to be replaced. you have to remove glove boxthe resistor is to the right of the heater blower moter
You'll find the heater blower motor resistor in the heater/air conditioner compartment. This compartment is location underneath the dashboard. This is the part that allows the heater blower motor to change the fan's speed.
bad blower resistor
The most common cause of the heater blower being on high only is the blower resister failing. The second most common problem is the blower switch going bad.