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peterpete190
peterpete190, Auto Technician
Category: Nissan
Satisfied Customers: 27634
Experience:  Over 17 years diagnosing and repairing vehicles.
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2003 nissan altima. I have no power to the ac compressor but

Customer Question

2003 nissan altima. I have no power to the ac compressor but if I apply 12 v directly to compressor it will work and blow cold? I have checked all the fuses and swapped the compressor relay already.
Submitted: 11 months ago.
Category: Nissan
Expert:  peterpete190 replied 11 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

Have you had the fault codes checked at all with a fully compatible scan tool to see what codes are set with this issue at all?

Was anything done on this model that may have caused this fault here?

Let me know so we can continue from here,thanks Pete.

Customer: replied 11 months ago.
Only codes in any module is a oxygen sensor code.
Expert:  peterpete190 replied 11 months ago.

Is this the 4 cylinder or 6 cylinder engine?

Customer: replied 11 months ago.
4
Expert:  peterpete190 replied 11 months ago.

O.k.,one last question here before I begin.Does your model have the AUTO heater and ac controls with auto temp settings or manual controls?

Customer: replied 11 months ago.
manual
Expert:  peterpete190 replied 11 months ago.

Check in the engine room fuse panel for the 10 amp fuse 34 and make sure it is good.If this is o.k. tap on the ac relay and see if the compressor runs while tapping on it or tries to run.If it does then the relay needs replaced.If these are all o.k. then we will need to test the signals at the ac compressor relay to see what signals are missing.

This can be the fuse at fault,the relay or an issue with the BCM not signaling the relay needing replaced or even wiring to or at the relay at fault.Below is a diagram of your ac system on this model here for the compressor if this helps you to test this.

https://www.dropbox.com/s/lo0ma1u8qkjaoj4/ac-07-28.gif?dl=0

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,a rating of 4 or 5 is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 11 months ago.
If I ground the blue/white signal wire at the back of the switch assembly the compressor comes on. Shouldn't this be a power wire?
Customer: replied 11 months ago.
I was using my test light to check for power and the compressor came on but doesn't cycle and stays on
Expert:  peterpete190 replied 11 months ago.

This should be a ground on the back of the switch from what I can tell on this here.

Is the compressor running now.Did you tap on the relay at all to see if the compressor came on?

Customer: replied 11 months ago.
I tapped no change. It will run and be cold as long as I probe this wire. If I shut the fan off or ac switch it stays running.
Expert:  peterpete190 replied 11 months ago.

This sounds like the switch itself is at fault here.You are introducing ground when you grounded this wire at the switch and caused the compressor to come on.It sounds like the switch is at fault and the heater/ac panel needs replaced.

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.A rating of 4 or 5 is appreciated

Thanks Pete

Customer: replied 11 months ago.
If that is the case and I am introducing the ground that the switch is supposed to supply why can't I get the compressor to shut off with the button or when the fan switch is in off.
Expert:  peterpete190 replied 11 months ago.

The only other thing I can think of here is your energizing the relay and the relay is not de energizing.If you have another relay in your fuse panel that is the same part number try swapping it and see if the ac operates properly then.If it does then it is just the relay at fault.

Customer: replied 11 months ago.
Its not the relay. That is one of the first things that was done.
Expert:  peterpete190 replied 11 months ago.

The only other thing I can see here myself is an issue with the switch needing replaced.