# Normal AC Refrigerant Pressure Range?



## TorJoe (Feb 29, 2020)

Hi,

Long story short: the ac of my 2013 Nissan Rogue is not working and I am in the process of eliminating various possibilities. One of these is the amount of refrigerant in the system. Hence my question:

With the engine off, what should the normal range for refrigerant pressure be? My understanding is that when the engine is off the pressure on the low pressure side and the high pressure side should be identical.

I do realize that what matters is where the pressures are at when the car engine and ac are running. But for my own reason I don't wish to turn on the ac (I have just replaced the pulley, the clutch plate, and the coil; I wish to make sure the ac compressor and refrigerant level are normal before I turn on the ac, lest there is another problem that may damage my new parts).

Is there a normal range for refrigerant pressure for when the car engine is off? I have come across various posts online where people say the normal range should be 25-40 psi on the low side and 200-270 psi on the high side. But this is for when the ac is running.

Thank you so much.


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## huesmann (Aug 18, 2011)

It depends on the ambient temperature and humidity.


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## TorJoe (Feb 29, 2020)

huesmann said:


> It depends on the ambient temperature and humidity.


Hi Huesmann,

Thanks for your reply. The figures on your chart, I believe, are for when the ac is up and running (hence the low side figures and the high side figures are not the same). I am interested in know the figures for when the ac (and the car) is not up and running. 

Thank you.


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## huesmann (Aug 18, 2011)

Static pressures will only tell you whether the system is pressurized, nothing about how much refrigerant you have in it.


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## TorJoe (Feb 29, 2020)

huesmann said:


> Static pressures will only tell you whether the system is pressurized, nothing about how much refrigerant you have in it.


I see, so there is no proportional correspondence between pressure levels when the ac is running, on the one hand, and static pressures, on the other?


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## huesmann (Aug 18, 2011)

Nope, not really.


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## TorJoe (Feb 29, 2020)

huesmann said:


> Nope, not really.


And I can't measure the pressures when the ac is running unless, well, I turn on the ac. I am hesitating to do that for the reasons you know from another post I have made about my clutch plate.


Argh!


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## huesmann (Aug 18, 2011)

What do you have to lose?


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## TorJoe (Feb 29, 2020)

huesmann said:


> What do you have to lose?


I fear that if the ac compressor is in fact locked or seized or otherwise for whatever reason offers much greater resistance than usual, and the pulley and the clutch engage, it may cause damage to these new parts.


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## raylo32 (Nov 25, 2006)

As Huesmann said static pressure will tell you only that you have "some" refrigerant and is only a function of ambient temp (assuming you have enough in there that it is a saturated system). But if the leak is really bad and the system is essentially empty the low pressure switch will prevent the compressor from engaging.

Have you checked the static pressure yet? What made you tear into the compressor in the first place without checking the pressures, relay, etc.??? This is a bizarre thread. It would help to check the basics first and give us some data.


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## huesmann (Aug 18, 2011)

If you've got your new clutch on your compressor and it's firmly clamped to the pulley, why not give it a whirl and see if you get cold air with the AC turned on in the cabin (this is basically an always-on condition)? If you get cold air, all you gotta do is shim the clutch enough so that it turns freely with the AC off, but engages when the AC is on.

Have you _checked_ your static pressure?


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## raylo32 (Nov 25, 2006)

Indeed... I have already asked him that TWICE, once in the other thread and once here. That is step #1. Still crickets.

All I got from his other thread is that my A/C quit working... so I replaced the *compressor clutch*??? How on earth did he make that leap?? As I mentioned there are a bunch of things in the circuit needed to engage the clutch and the first one to check is refrigerant. Then the relay. Maybe the switch. Clutch failures happen but not the most likely scenario. Now maybe he knows more about this but he sure hasn't told us anything.



huesmann said:


> Have you _checked_ your static pressure?


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## TorJoe (Feb 29, 2020)

Hi,

I did check my static pressure before replacing the pulley, clutch, and coil. According to my user manual, if the static pressure is above 50 psi then there is enough refrigerant for the system to start. Whether the pressure will be within specs when the ac is running is a different question. 

The old pulley, clutch, and coil show clear signs of damage. The face of the clutch is rusty, the rubber in the clutch is partially melted, and the black rubber lining the surface of the coil is all gone. 

The system is able to start and produce cold air after I have replaced these parts. Now I am on to testing whether the system has sufficient refrigerant to function efficiently. 

Thank you so much for your input. You've been most helpful.


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## oil.equipment.2020 (7 mo ago)

*Normal AC Refrigerant Pressure Range*


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## HotRodx10 (Aug 24, 2017)

Thread is 2 years old, and reposting the title of the thread adds nothing of value.


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