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Trying to get the bugs out of this car I've got.

Its an 05 Altima 2.5S, and the blower stopped blowing.

I put a new resistor in the place of the old which did have a burn on one of the leads in the connector on the resistor.

After that the fan still wouldn't turn on, so I hooked it up to a battery for testing. The fan worked fine wired straight to a battery.

Put everything back together, and it ran fine. Next day nothing.

I pulled tested the fan again, and it ran fine. I hooked everything back up, and decided to check the cabin filter out. It was in really bad shape so I put in a new filter.

Turned on the blower switch, and the fan worked fine.

Tried it again last night, and nothing, dead again.

I'm not getting it, wtf is wrong with this thing? Also, checked the fuses, and all is well there.
 

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09 Altima 3.5SE 6MT Sedan
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6,365 Posts

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09 Altima 3.5SE 6MT Sedan
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6,365 Posts
Where is the blower motor relay located?

Thanks.
M, see wiring diagram page ATC-32 here (use MTC.pdf if you have the manual AC controls). There is no relay per se, and given the symptoms the fuse is also okay. The Fan Control Amp is a type of transistor (MOS FET) which is used for motor speed control. Since it works some of the time, I'd say it's ok.

I think you need a new blower motor...probably have some carbon on one of the rotor winding pads, and like a missing tooth on a flywheel...when you try to start it in that position, it just doesn't work. Spin a couple of degrees and Shazaam...
 

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09 Altima 3.5SE 6MT Sedan
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6,365 Posts
Ok d0ugmac1, I will give it a try, thanks.
If you get it in the 'no start' condition, try a shop vac or something to move the blower fan blades and see if it auto starts from there. If it doesn't it could be the transistor module...they do heat up and the solder connections can fail.

You might be able to borrow some parts to debug with....if she doesn't notice.

You could also remove the Control Amp (transistor module) from the path, and simply ground that side of the blower motor windings...that should make the fan spin at full speed everytime. You could even use that to test the rotor theory...if grounding doesn't make the motor spin, it is the motor and neither the Control Amp, nor the HVAC control unit itself...which is a 3rd possibility not previously discussed :) (Debugging between the HVAC control and the Control Amp will be a little trickier...essentially the control module sends voltage pulses that turn the transistor on and off very quickly...the duty cycle of those pulses determines the motor speed. With a multimeter you should see the average voltage which should increase with desired fan speed. If it's stuck at zero during a non-start condition...it's probably the HVAC control unit that needs replacement. Solder joint problems also apply to the HVAC if you feel the need to crack it open to inspect further.
 

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M, see wiring diagram page ATC-32 here (use MTC.pdf if you have the manual AC controls). There is no relay per se, and given the symptoms the fuse is also okay. The Fan Control Amp is a type of transistor (MOS FET) which is used for motor speed control. Since it works some of the time, I'd say it's ok.

I think you need a new blower motor...probably have some carbon on one of the rotor winding pads, and like a missing tooth on a flywheel...when you try to start it in that position, it just doesn't work. Spin a couple of degrees and Shazaam...

It does have a relay per se.

See page PG-11 in the service manual.
 

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09 Altima 3.5SE 6MT Sedan
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It does have a relay per se.

See page PG-11 in the service manual.
That makes so much more sense now! Thanks...always enjoy being proven wrong...you get to learn something!
 
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