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Re:2014 nissan pathfinder front HVAC blower motor inop
Hello all, Checking out an inop front hvac blower motor, tested power to motor (none) & fuses 17 & 27 in ip fuse block. Fuse 27 is good and has power on both legs however fuse 17 has no power to either leg. Looking at wire schematic shows both fuses 17 & 27 are powered by the same pin on relay. The blower relay is on the back of the ip fuse panel, so my test results lead me to believe there is a broken circuit from relay pin to fuse 17 which is internal to the fuse block. I powered fuse 17 with a fused wire and blower operates. I'm not understanding the system circuit needing both fuse legs to power the blower motor, could someone please explain this theory to me ? Thanks in advance, Matt
Edit: Sorry but my guy did initial testing of fuses & claimed he tested power on fuse 27. I just rechecked powers & fuse 27 DOES NOT have power as well as fuse 17. Looks like the fuse/ relay box is powered by 100 amp fusible link by battery (which does have power coming into box) but nothing at either fuse or coming into relay. Still looks like loss of power internal to relay. Still would like to understand why it has 2 15 amp fuses powering same power wire to blower or my wire diagram is wrong?
Looks like to me that my diagram is a partial view. I have attached my diagram for reference. Anytime you see a dotted line around something is because it is just a partial view so im sure there is also power going somewhere else that isnt shown in this diagram. However thats not your problem, sounds like your problem is the relay and/or the circuits going to the relay. Hope that helps!
i have found no power on white wire coming to relay from body control module. BCM has no codes. This is my first go with nissan system not sure what is commanding bcm to power relay. i think i'll have to test white wire AT bcm when i get back to it tomorrow unless someone has another suggested method.
hi everyone, according to that wiring diagram, the blower receives positive and negative. what I understand is that the internal module the blower has, depending on the signal the AC unit sends, works to a proper speed. you should try to read with a scope the signal in the white wire whenever you turn into different speeds the AC module blower commands. If you confirm that variable signal, the blower is failing.
Blower motor and wiring from relay to blower are confirmed good. The problem is relay is not being energized from the BCM. The HVAC module IS seeing blower fan speed from switch according to HVAC scan data
No codes in either module. I haven’t tested directly at bcm yet. I should get back to it tomorrow. I would like to know if the bcm gets blower relay command directly from HVAC module fan switch
Does this one have the a/c and a/v switch assembly or just the a/c switch assembly (base radio)?
The BCM gets the blower motor on signal from the a/c auto amp (ac module) via CAN. There is a pid in the BCM that says blower motor fan switch on/off. What is that reading?
The a/c auto amp provides the pwm signal to the blower motor. Are you able to command the motor on from the hvac module?
Does the rear blower motor work? That one shares the relay power from the BCM, so if that works, you know the BCM is putting out something.
Sorry forgot to mention the rear blower wasn’t working either. Like you stated tutti it uses the same relay. I was able to see the fan selections in HVAC data. I found the bcm to be the problem. Replaced the bcm and had it programmed and that cured the problem. So thanks for all of the responses it’s appreciated. I think a moderator has to label this fixed as I don’t see a way for me to do it. One question for you all (maybe tutti nissan tech can answer). The relay feeds to 15 amp fuses and both of those fuses connect to the same feed wire for the front blower. What is the purpose for that design? Appreciate any insight I’m just curious
Matts Auto wrote: One question for you all (maybe tutti nissan tech can answer). The relay feeds to 15 amp fuses and both of those fuses connect to the same feed wire for the front blower. What is the purpose for that design? Appreciate any insight I’m just curious
They probably did it for reliability. 30A is the max for the mini, and smaller, fuses and just because they make one that big doesn't mean it'll hold up long term.
That’s the only logical thing I could think of as well but I just seem to let things bother me until I get the full understanding of how it works and intended purpose. Thanks guys for your responses very appreciated
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