My 2012 Nissan Altima 3.5L ac fan will not shut off completely. It will increase in speed, but never cut off. I did had the ac compressor replaced several months ago, but this is new. I have read that the 2012 Altima's do not have a blower fan resistor? If so, it may be the motor blower relay? Is this behind the left side fuse box? Thanks for any info!

2001PearlPathfinder wrote: ↑

Tue Mar 08, 2022 12:37 pm

My 2012 Nissan Altima 3.5L ac fan will not shut off completely. It will increase in speed, but never cut off. I did had the ac compressor replaced several months ago, but this is new. I have read that the 2012 Altima's do not have a blower fan resistor? If so, it may be the motor blower relay? Is this behind the left side fuse box? Thanks for any info!

That's correct, there's no resistor or VBC. The motor is a brushless DC (BLDC) type with a built-in control network. The Blower Relay won't be your problem, it can only provide power to the blower but can't make it run. Assuming it isn't a wiring issue, there are only two possible culprits, the BLDC controller inside the blower or the HVAC control head. Unlike most other Nissans, the gen4's don't have a separate HVAC control head and control display, they're integrated into the same unit called a Front Air Control (FAC). On a gen4 the setup is the same whether you have Auto A/C or Manual. The blower is easily accessed behind the glove box and easily changed if it's bad. To diagnose it, take the connector loose at the blower and put a voltmeter on the thin Blue/Yellow wire. The BLDC uses "negative" control, near 0V is full speed and 9~10V is off. See if the voltmeter responds the way it should when you work the speed dial. If so, the problem is in the BLDC, if not it's in the FAC.