Air conditioner and HVAC wiring diagrams

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.

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

The relay was in the diagram I attached in the beginning. I attached the location of the relay for you.

Roy

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.

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

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!

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.

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?

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?

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.

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.

Thanks for the update Erin664.

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?

Did you ever fix your problem with the AC/heater not turning on? If you did what was it?

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

Yes, she did. Her last post detailed what fixed it.

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?

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

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.

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

Here are some guides and some diagram (below) that will help us get the problem fixed. Check it out (below)

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

Please let us know what happens.

Cheers

hi james
i was reading all question and anwser in the forum regarading my a/c probem ,I find out that on sept. 25, 2008 ( dsdhornet) his code name ,ask the same question as my problem! i was thinking counld it be the temp sensor on evaporator or the temp control amp causing this problem , i already replace the triple sw but it don't make defference
pls advise thank's fixsky

It could be any one of the sensors or controls on your system. It sounds like it could be the problem

hi james
yeah, this could be one of the sensor but i don't have specs. for testing this thermo cntrl amp? and i'm a bit lost of this system coz when they call it thermo cntrl amp. this must be a module with printed broard ,chips resistor ect. in the small box connected to the harness ,and when i check it , its only three wire harness that go in to the a/c evap housing i don't know what on the end of this three wire . like older nissan i see a small box stick on the side of the evap case call it thermo cntrl amp, and also this nissan altima was made MAY . 2001 may be we barcking the wrong and get the wrong info. pls help thanks fixsky

We have a lot of problems with import(Japanese) wiring diagrams not matching what is actually in the vehicle. Many times we just have to read between the lines. Usually, unless you have the diagnostic unit, there is very little the owner can do to isolate an electronic problem. You can use the"well that didn't fix it, let's try this" approach, but that can get expensive.

hi james,

now i would like to say that "case is close" to this repair thank's for the help , i just change the temp control amp for the a/c located in the evap housing and it fix the problem
thank's fixsky

Glad you got it. Anything else, youi know where to find us.

Hi Fixsky,
Looks like I have the same issue as you described and your solution seems to perfect fix for mine. I would like to get information on the following:
1. Where exactly is the Evap Housing Located on the Altima?
2. Where can I buy the Temp Control Amp? Please provide any part #, if you have it.
3. Does this fixing need any special tools?

Thanks in advance.
-Jay


[quote:e6e38a5ec2="fixsky"]hi james,

now i would like to say that "case is close" to this repair thank's for the help , i just change the temp control amp for the a/c located in the evap housing and it fix the problem
thank's fixsky[/quote:e6e38a5ec2]

The evaporator is under the dash in the same box as the heater core. No special tools required, it's just a miserable bugger to get at.

Thanks James W. I appreciate your input and will try it over the weekend. I was out of town for a while and didn't get a chance to see your reply until today and thus the late response. Thanks again.