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Discussion Starter #21
Ok, so if the IPDM test cannot energize the AC clutch, then your next step is to check/replace the AC fuse and/or relay in the IPDM.

You won't see anything move, but you will hear it, and should feel a thud if touching the AC pulley.


Discussion Starter • #20 1 h ago
After holding my hand on the hi side small AC line where it connects to the compressor I can confirm the clutch is engaging and demagnetizing the 5 times like it’s supposed to during the ipdm test, so it’s something else causing my compressor not to come on with my climate controls.

i am up for any suggestions and I do have a multimeter and other electrical testing tools, but I do not know the switch locations on my 2012 Altima
 

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09 Altima 3.5SE 6MT Sedan
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Go back to the thread I linked in #17, and read the bit about the low pressure switch. Disconnect it and short the harness terminals....if the AC compressor kicks on (engine running, max cool selected) then you have a clue.
 

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Discussion Starter #23
Go back to the thread I linked in #17, and read the bit about the low pressure switch. Disconnect it and short the harness terminals....if the AC compressor kicks on (engine running, max cool selected) then you have a clue.
I know quiet a bit about these safety switches as I am a gas technician/ residential HVAC tech but I don’t know much about these car systems as far as the locations of these switches.

If I can find the switch and wire harness I would be able to bypass the switch easy enough as this is same principals as residential HVAC process of elimination.

is there a way you can point me to wherethis switch would be located?
 

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09 Altima 3.5SE 6MT Sedan
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Here you go, the 4 things that usually go wrong, and their location on a 2012 Altima:

1. ac clutch/compressor
2. ambient temp sensor
3. pressure switch
4. ac clutch relay

100962
 

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09 Altima 3.5SE 6MT Sedan
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and how to test the 3-wire pressure switch without breaking it (ie ignore my comment about shorting...that's for older model cars)

100963
 

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Discussion Starter #26
and how to test the 3-wire pressure switch without breaking it (ie ignore my comment about shorting...that's for older model cars)

View attachment 100963
I have pulled the ambient sensor, tested for continuity though the switch and only get OL no continuinty, is this switch normally open or normally closed?

If this switch is normally closed like I think then I believe this could be my problem!
 

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Go back and look at the ambient temp sensor description in post #12, it is NOT a simple on or off switch. Rather, it provides variable numbers and the ECM itself is the decider of on or off.
 

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Discussion Starter #28
Go back and look at the ambient temp sensor description in post #12, it is NOT a simple on or off switch. Rather, it provides variable numbers and the ECM itself is the decider of on or off.
I am getting a OL reading on my meter, even at outside temp 85+ F , it’s like the switch has no continuity /ohm reading resistance At all
 

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09 Altima 3.5SE 6MT Sedan
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As above the ambient sensor is a variable resistance...if you get 0 or infinity (OL?) then it's in need of replacement. The table in post #12 gives sample resistance values. For instance, at 85'F, it should read approx 1,800 ohms or 1.8Kohm
 

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Discussion Starter #30
As above the ambient sensor is a variable resistance...if you get 0 or infinity (OL?) then it's in need of replacement. The table in post #12 gives sample resistance values. For instance, at 85'F, it should read approx 1,800 ohms or 1.8Kohm
I have no ohm reading on the old ambient sensor, I replaced with one from the dealership with absolutely no change whatsoever, clutch coil still not engaging from front air controls
 

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09 Altima 3.5SE 6MT Sedan
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What's the ohm reading on the new sensor?
 

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Discussion Starter #32
I installed it directly at the Nissan dealer, as I was heading on 200 km round trip and really hoped my AC was going to work, I already planned on testing the new switch, I will get back right away
 

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Discussion Starter #33
Ohm reading on new sensor is 1.9 k ohm at around 30 C , normal reading, still not powering on clutch for AC, I am going to check power again at the harness right now , and confirm ground
 

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Discussion Starter #34
I have confirmed normal reading on new sensor, and again confirmed 5 volts at harness connector to battery ground, I am wondering where the ipdm harness is located to test for continuing ground from harness to ipdm?
 

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Discussion Starter #35
I found harness 201 with the same wire coming from ambient sensor, and there is continuity, as well as 5 volts on other wire to ground..... where should I look next ?
 

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Discussion Starter #36
To reiterate -

my ipdm auto self test does send power to the coil and it clicks on and off 5 times, I had a faulty ambien sensor, I replaced it, confirmed 5 Volts to ground at the ambien harness, and confirmed continuity between the ambien harness terminal 2 to the same wire on the ipdm harness, and there was confirmed continuity.

I still have no AC whatsoever and I don’t know what would be the next most likely thing to cause these issues
 

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09 Altima 3.5SE 6MT Sedan
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the variable pressure sensor...see post #24, it's #3. This is a 3 wire sensor which puts out a variable voltage based on system pressure. See post #25 and try the debug test there.
 

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Discussion Starter #38
the variable pressure sensor...see post #24, it's #3. This is a 3 wire sensor which puts out a variable voltage based on system pressure. See post #25 and try the debug test there.
How do I access my ecu / harness?
It says passenger side instrument panel which I had removed but don’t see the ecm anywhere.... I do see a mounted plate beside my battery under the hood that looks like an ecm..... thanks in advance
 

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Discussion Starter #39
I have looked through the Nissan website and it says the ecu is located behind my Front passenger Instrument panel, I have heard from others I need to remove my glove box for this.... this makes no sense to me.

after confirming part number with actual breakdown of my 4gen model 2.5 engine I have almost confirmed that my ecu is the unit that I had in question on my last post... just looking for any confirmation from others on this
 

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09 Altima 3.5SE 6MT Sedan
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Beside your battery

100989
 
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