Trying to narrow this down to the faulty component with no luck yet. I do have the FSM in hand and I'm looking to see what troubleshooting steps I'll be able to perform. Right now the fan is working fine so I went out and got voltage and ground continuity tests done at the fan connection. Voltage starts at 11.8 with the fan off and gradually decreases with each fan step to 10.8 at the highest speed. The fan itself spins easily, no obstructions. The 2 15A blower fuses looked fine and have been reseated.

I've watched it when it doesn't work and observed that it usually starts to spin and then stops. I think I got a reading off of the blower connection when not working and the voltage was way low, maybe 6v. I need to confirm that again when it's not working. The FSM talks about using an oscilloscope which is not going to happen in my toolset.

AC on or off doesn't matter. Air flow position also doesn't matter although I don't think I've tried circulate vs. outside (doubt that matters). Auto vs manual also doesn't seem to matter. One thing I've noticed is hitting the defrost button when the fan doesn't want to spin sometimes makes it work. Possibly because the defrost mode starts immediately at full fan speed instead of gracefully powering up? That method does not work every time for me.

Any one else been through similar symptoms or have suggestions for further troubleshooting?

 

Intermittent faults are a PITA, you may have to catch it when it is messing up or wait for complete failure. The decreasing voltage when increasing fan speed positions corresponsds to the FSM reference to using a scope to observe the duty cycle. My guess is it is the controller, "A/C auto amp".

 

Was able to catch it today while it wasn't working. I was sitting in the garage and watched the voltage accros blue and black at the fan start at 1.5v and slowly climb very steadily over about a minute until the fan finally kicked on. That almost seems like what would happen while the car is warming up where the fan won't turn on until there's some heat in the coolant. The only catch is I had the fan set to manual at almost full till. So that would make me think the controller is out of whack.

My other observation though is when the fan isn't working while driving, it will often kick in after hitting a bump. On the other hand, it never shuts off after hitting a bump. Once it starts working, it stays working for that trip.

Don't really know what to think for sure right now. I wonder if my wife's 04 maxima blower is the same so that I could swap and test. Might have to look at that.

 

I shouldn't add to this post before I find the definite issue, but I'm doing it anyway. Dug further into the FSM, not sure how I missed this before but there is an excellent HVAC self diagnostic built into Nissans. Ran that easy process and got a 25 code which points to the sunlight detector. I'm zeroing in on that now. Currently this issue has become consistent, no longer intermittent. Car will run for about 5-10 minutes before the fan kicks on at all. Display will show the fan spinning up as the coolant heats up, but the fan isn't actually turning until x number of minutes go by.

Oh and it's cold out in South Dakota!! Thank God for remote start, but still need to fix this. Will play more and report back in case anyone else runs into this.

 

The 25 code didn't pan out. The FSM talked about performing this test in direct sunlight. I had a trouble light pointed straight at the sensor when I tested. I retested in sunlight and got no error codes. Can't fool Nissan I guess.

When the weather warms up, I really need to tear into the dash and check for loose connections. I'm finding it odd that when it's really cold the fan never kicks in until the car has been running for about 10 minutes. In these cases, I've now also observed the fan kicking on and then immediately shutting off but only on rare occasions. When it warms up, it will often kick in right away.

I keep pumping my own thread in the hopes that someone else is or has had similar symptoms.

 

I know that you posted some time ago, but I am having the same exact issues you encountered. Did you ever find the problem? I changed out my blower motor and still the same thing.

 

Praise God, finally someone else in the same boat Well after looking at the FSM closer, I realized that the auto a/c amp (which is probably what I need to replace) is very easy to remove. It is located in the assembly at the top of the dash where the clock is. I popped that out and after checking continuity on the wiring harness and motor, I'm fairly confident it's not just a loose wire. I also brought that whole assembly into my house for several hours to warm it up and then brought it back outside but that had no effect. I'm currently checking on pricing for the a/c auto amp circuit board.

 

My car is at the stealership as we speak. They assumed it was the blower motor as well and tried to replace it with no avail. I will let you know what they say or do when I finally get my car back. It's supposed to be -13 in MN tomorrow morning, I hope they figure it out.

 

Must be one of the 2 Minneapolis dealers? I don't have one in Sioux Falls, just Nissan dealer. So you had similar symptoms long term or just recently? I searched all the nissan forums and couldn't really find anyone having the same intermittent issue I've been having. Most climate control issues typically led to the auto a/c amp.

 

Yeah, Bloomington. This is the first winter with my car and it has been doing this ever since it got cold. The blower ran fine spring-fall, but when it got cold out is when the blower wouldn't kick for some time. How long it takes to turn on changes though, seems like the colder the engine, the longer it takes to come on. On a normal day after sitting in my garage overnight, it will turn on in roughly 10-15 minutes. I once left it over night in St. Cloud outside, and it didn't turn on for over 45 minutes on my drive home. Very strange. I saw one other thread with our problem, but nobody had responded to him. They were supposed to be working on my car first thing this morning and I haven't heard anything back yet, so that probably isn't a good sign.

 

Well I certainly appreciate any feedback you can leave after yours is resolved. Part numbers, cost, whatever. I'm an 06 coupe 6MT just outside of warranty. My drive to work is only 5 minutes so it sounds like you've been a little more frozen than me.

 

I just got off the phone with them and they overnighted an auto a/c amp.
They think that is the problem as well. I will let you know tomorrow afternoon if that corrected the problem. My normal drive to work is only 15 minutes, so not terrible. It would usually turn on when I got close to the office.

 

It sounds like you're under warranty?

 

Yeah, I bought the car used last spring and purchased the warranty with it. I'm happy I did, I have had some problems with the car that I would not like to fix on my own.

 

How'd it go?