The Nissan Quest blower motor is a combined unit that is composed of a motor and a fan that looks like a hamster wheel. Its function is to draw air from the outside through the heating and cooling elements, and force hot or cold air through the ducting and interior vents. If you notice that the air circulation is weak or the vents work on one speed, there may a problem with your blower motor. You don't need to call the mechanic yet. These simple troubleshooting tips will help you determine and maybe fix the blower motor on your Nissan Quest.
The problem isn't the fan or the motor, but the resistor. The blower motor resistor controls the speed of the fan (low, high, and mid-range). If the resistor is faulty, the motor bypass the resistor and directly sends power to the blower. As a result, the resistor cannot control the blower speed and you will not be able control it with the A/C switch. Changing the resistor will correct this problem. Refer to the owner's manual to locate the blower motor resistor. Change the resistor and test the blower motor.
Again, the resistor can be blamed for this problem. Since it controls the speed of the blower motor, a faulty blower motor resistor may reduce the amount of airflow at different speed settings. This problem can be solved by replacing the resistor.
An average DIY mechanic often go for the obvious-and change the resistor or the fuse or replace the entire motor component-if there's a problem with the blower motor. But if the initial repairs fail, he has nowhere to go. Remember that the system has a ground that is important to complete the circuit. If there's power at all ranges, but there's no response from the motor, check the ground. After a while, ground connection can become loose or corroded, resulting in motor malfunction.