Diagnose and fix Nissan blower motor doesn’t work
Nissan blower motor inoperative condition is fairly common in late model Nissans. As you can see from the wiring diagram below, the system uses a relay and two fuses. The relay must work in order to provide power to the two fuses. The blower motor relay is a high failure rate item. But here’s how to diagnose the system
Step 1: Test the Nissan blower motor fuses
Check fuses 21 and 22. They’re located in the fuse block behind the left end of the dash
Step 2: Remove the Nissan blower motor relay
Pop the relay out of its socket (it’s also in the same fuse block as above).
Step 3: Test Nissan blower motor relay continuity
Using a voltmeter set to the OHMS scale, check for continuity on the control coil terminals 1 and 2 of the relay itself. If you see continuity, the control coil is intact. If not, replace the relay.
Step 4: Test Nissan blower motor relay for ground
Check for good ground on pin #2 in the relay socket. If you don’t find good ground, clean the ground connection for the relay, located behind the left end of the dash.
Step 5: Test Nissan blower motor for power
Battery voltage at terminal #5 in the relay socket. It should be hot at all times.
Step 6: Check for power into blower motor fuses
Reinstall the relay. Turn the IGN on and select a blower speed. Then check for power coming into fuses 21 and 22. If you don’t see battery voltage at the fuse, there are two possibilities:
1) The relay is bad. Replace it.
2) The control coil isn’t getting power from the BCM. Backprobe terminal #1 of the relay with the IGN switch on and blower switch set to any speed. If you don’t see battery voltage at this terminal, check for battery voltage directly at the BCM connector #6P. If you see battery voltage there, look for an open in the wiring harness between the BCM and the relay. Fix the open.
How the Nissan blower motor works
When you turn on the blower motor, the relay sends power to fuses 21 and 22. Power flows from fuse #21 to the Front Air Control. The relay also sends power to fuse #22 and then to the blower motor.
When you turn on the blower motor, the front air control tells the BCM to provide power to terminal #1 of the control coil on the blower motor relay. The control coil energizes and closes the contacts to provide power to the two fuses. Once the front air control sees power from fuse #21, it provides pulsed power to the Nissan blower motor on the blue/yellow wire to control blower motor speedPosted on by Rick Muscoplat