Air conditioner and HVAC wiring diagrams

Tiny
ECLIPSEKRYPT
  • MEMBER
  • 2012 NISSAN ALTIMA
  • 2.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 10,000 MILES
I changed everything of the A/C compressor about a year ago. Now the car has A/C sometimes and other times it doesn't. For example today I have ac but yesterday I didn't. When it works it is perfect, when it doesn't it is hot. This is what I changed:

Expansion valve
Dryer
Compressor
Condenser
A/C filter

Thanks in advance.
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Monday, February 10th, 2020 AT 8:48 AM

30 Replies

Tiny
ASEMASTER6371
  • EXPERT
I attached a wiring diagram for you to view. Verify power to the compressor when the Ac is not working. This guide will help witht he HVAC air conditioner wiring diagram below.

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (Below). Please let us know what happens.

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Monday, February 10th, 2020 AT 10:26 AM
Tiny
ECLIPSEKRYPT
  • MEMBER
Roy,

My mechanic is telling me that other than that fuse (10a) there is a relay. I have tried searching and Googling it and cannot seem to find one. I just see that fuse. Do you know if there is any?
Thanks
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Tuesday, February 18th, 2020 AT 6:58 AM
Tiny
ASEMASTER6371
  • EXPERT
The relay was in the diagram I attached in the beginning. I attached the location of the relay for you.

Roy
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Tuesday, February 18th, 2020 AT 7:14 AM
Tiny
VOLZELECTRIC
  • MEMBER
  • 2007 NISSAN ALTIMA
  • 2.4L
  • 4 CYL
  • 250,000 MILES
Fuses replaced, all good, all three of them. The relay checks good. The blower motor was bad so motor is new. Reading 13.75 volts dc from hot to ground at motor connection and still motor does not turn. Put twelve volts to motor and it turns. Probably Controller circuit board? Operates variable speed by ground wire? I bought a new controller out of wrecking yard they said it worked. I installed the controller and still blower motor does not work. Checked fuses, swapped relays still no go. Are the sensors in series prior to the motor. I need the air conditioner wiring diagrams please.
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
KEN
  • ADMIN
Hello,

It sounds like you have a broken wire somewhere here is the wiring diagrams (below) and a guide to help you do some testing and get the problem fixed.

https://www.2carpros.com/articles/how-to-check-wiring

Please run some tests and get back to us we are interested to see what it is.

Cheers, Ken
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
ERIN664
  • MEMBER
  • 2007 NISSAN ALTIMA
  • 60,000 MILES
The fan switch control for the AC/Heater comes on like clockwork about twenty to thirty minutes after driving the car. I have manual temperature controls and replaced the fan switch control assembly with no luck. I have had better success when I place a space heater in the car on the passengers side pointed towards the console for thirty minutes then remove it and start driving, the heater fan motor will start after only five minutes of driving, sometimes right away. It will run for hours once started and sounds perfect, but if I stop the car for an errand leaving it off for fifteen to twenty minutes, it will take fifteen to twenty minutes for it to come back on. During the summertime, it is the same pattern with the AC it will take five to ten minutes for the AC to come on, but winter time seems to take much longer. Heat only comes on ten to twenty minutes after running. I changed the blower motor got new one and still does the same thing. Can you please help me figure this out. I also brought it to my neighborhood service station and they do not know what is wrong with it either?

Please advise. Thanks!
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
RIVERMIKERAT
  • MEMBER
I have attached the schematics for you to use while testing. But it sounds like a relay is giving you the trouble they can come and go like that. Use this guide to help test the problem.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Please run this test and get back to us so we can continue helping you.
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
ERIN664
  • MEMBER
Thanks for those. However, when I tried printing them they came out all blurry. I am unable to read the text at all. I tried saving them and printing from my desktop but that did not help. Is there anything you can suggest?
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
HEATHERGLOVINSKY
  • MEMBER
I have the same issue. The problem does not repeat itself when I drop it off at the dealership so they are unable to troubleshoot it.

I have a 2007 Nissan Altima. The issue began in November 2012 (just before the five year warranty ended). I woke up early to go to work, it was cold outside and the heating or A/C would not turn on. There is absolutely no noise or air blowing out of it. I have tried turning the car off and on again but this only works occasionally. After several minutes (two to ten minutes), the A/C and heating unit will start blowing air.

It seemed to happen more often last week when the temperatures were as low as the mid twenties at night.
The dealership changed the blower motor, control head, and recharged the A/C in November 2012.

Now, the warranty is expired and the dealership can not troubleshoot it. I took the car in Friday night and it worked perfect all day Saturday. And of course it acted up for us Sunday morning! It is difficult to get it to the dealership when it is acting up.

Anyone else been able to troubleshoot this issue?
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
RIVERMIKERAT
  • MEMBER
The blower motor is powered by a relay. Check the image attached. It shows the location for the blower motor relay. See if it is energizing as soon as the blower is switched on.
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
ERIN664
  • MEMBER
I figured out the problem and solution We did exactly what you said and now we have heat any time we want it! The radio only works when it wants now, but we know how to fix that. Just have to buy new relay they are about $30.00.

Hi, I was able to fix the problem, the blower motor works great now. Here's what I did. That relay is located in the instrumental panel fuse box ( behind the fuse box). Remove the cover for the fuse box, you will see the fuses, unscrew one screw next to it, and there is one more screw to be removed, remove the panel below the steering wheel, it is very easy just pull it down. Now you have easy access to fuse box, on the other side of the box there are four blue identical relays ( part number ends on 42. There is about ten digits number). Relays are located like this. *__**__* ( relay 1, space, relay 2 relay 3, space, relay 4). Blower motor relay is relay 1. Ideally would be to replace it ( you can buy it at the dealership or online). What I did, I replaced relay 1 and relay 2 ( relay 2 is for radio), everything is working great both blower motor and radio, if one day radio stops working I know what to fix. But I need heater more than radio, specially living in Minnesota.
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
RIVERMIKERAT
  • MEMBER
Thanks for the update Erin664.
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
ASIA TARTELL
  • MEMBER
  • 2006 NISSAN ALTIMA
  • 4 CYL
  • AUTOMATIC
  • 141,000 MILES
When driving home from work, fifteen minutes into the drive my AC just stopped working and was blowing hot air. I tried to add Freon but it seemed like the pressure was too high and the car was rejecting the Freon. I shined the flash light on the compressor and noticed it was not spinning/moving. I usually have bad luck at mechanic shops and getting ripped off, so my friend who is pretty knowledgeable about cars is helping me. I have spent hours trying to charge and diagnose. I am stuck and have no idea what to do next. Any Ideas to help?
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
FELIXFLORES
  • MEMBER
Did you ever fix your problem with the AC/heater not turning on? If you did what was it?
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
KEN
  • ADMIN
Hello,

It sounds likes the Freon has enough for the system to kick on. Here is a air conditioner wiring diagram (below) and a guide on how to do some testing. There are several fuses and a relay that runs the system.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

and

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Please let us know what happens, we are interested to see what it is.

Cheers, Ken
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
RIVERMIKERAT
  • MEMBER
Yes, she did. Her last post detailed what fixed it.
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
ABEL GONZALEZ
  • MEMBER
  • 2003 NISSAN ALTIMA
  • 2.3L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 125,000 MILES
Pressure sensor wires were damaged by a mouse. The wiring is repaired but A/C compressor still not engaging. I checked for power and grounds. At the A/C compressor relay all power sides are there but no ground is being command it to relay. Freon pressure is good Can it be the ECM nor BCM?
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
SCGRANTURISMO
  • EXPERT
Hello,

Ground is provided by the CPU located in the Intelligent Power Distribution Module Engine Room. That is located on the right front of the engine compartment behind the headlight. The CPU provides ground for the AC Relay, Cooling Fan Relay 1, 2, and 3, as well. I have included a wiring diagram for the Air Conditioning Circuit in the diagrams down below.I have also included testing for the CPU as well. Please use it to check the CPU and get back to us with you are able to find out.

Thanks,
Alex
2CarPros
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
ABEL GONZALEZ
  • MEMBER
Scwickestang thank you for your help CPU was the problem.
Thank you for the diagrams and the time you spend to help me out you have saved me a large amount of money because I was about to replace the ECM and BCM.
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)
Tiny
FIXSKY
  • MEMBER
  • 2001 NISSAN ALTIMA
My a/c will come on sometime will not, the air is getting cold when its on and go up to cycle stage when it reach the correct temp. Work fine, sometime when you turn off the car and sit for 30 min to 1 hour when you start back up and drive and turn on the a/c sometime it will not come on and I see the clutch engage for spit a second it trying to engage but it doeskin continue, I already replace the triple switch on the top of the dryer w/ 4 wires connector still the same make no deference and when I ground the red wire from the sensor it work but a/c always on even you off the a/c sw. What could be the problem? Can you give me the complete wiring diagram for air conditioning with the correct color coding and the location of ECM and the thermo control amp. Where they hide it. Thank"s fixsky
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Tuesday, May 25th, 2021 AT 11:15 AM (Merged)

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