How to recharge A/C On A Nissan Rogue?

[zengshengliu]

One thing I still don't get it is that should I hold the can up right or up side down? Some company say up right, some say up side down.
The problem I see with up right is that sometimes it let air go in to the system(which happen to me today and cause the compressor to kick on only for a second and shut off again)

[kilogram]

How often should the ac be re charged?

Technically, never. It's a sealed system and refrigerant is not a consumable. If it needs to be recharged, there is a leak somewhere that needs to be addressed.

[ImStricken06]

How often should the ac be re charged?

Technically, never. It's a sealed system and refrigerant is not a consumable. If it needs to be recharged, there is a leak somewhere that needs to be addressed.

not true. a normal operating system will still leak a tiny bit over the years. if it leaks every couple months, then you know you need to replace seals somewhere. but if it leaks out over a span of 2-3 years; its fine.

[kilogram]

not true. a normal operating system will still leak a tiny bit over the years. if it leaks every couple months, then you know you need to replace seals somewhere. but if it leaks out over a span of 2-3 years; its fine.

Do you recharge your refrigerator every 2-3 years? An AC refrigerant system is sealed and should not leak at all. If you need to recharge it, the appropriate course of action is to test for leaks, period.

A single recharge after maybe 10-15 years is acceptable, though the system should still be checked for leaks. A recharge after 2-3 years means there IS a leak and it needs to be addressed. The system should not leak at all.

[ImStricken06]

An AC refrigerant system is sealed and should not leak at all.

in theory, YES YOU ARE CORRECT.

but in reality, it doesn't work perfectly like that. over time seals will allow the pressurized system to slowly release (usually due to someone not using their a/c system for long periods of time, and not lubing the seals), thus easily bringing you down from 35psi to the threshold of 25psi in as little as 2-3years. often times once the seals are relubed from use, they are back to their good condition - but the system requires a slight top off.

its just like tires: they too are a "sealed" system.... but we all know that over the course of a year, they too release pressure, needing to be topped off. dose that mean that the tires, valve stems, need to be replaced??? not unless they are deflating weekly.

[kilogram]

in theory, YES YOU ARE CORRECT.

but in reality, it doesn't work perfectly like that. over time seals will allow the pressurized system to slowly release (usually due to someone not using their a/c system for long periods of time, and not lubing the seals),

That is why OEMs design the A/C system to run with the defroster (in addition to pulling moisture from the air)- to keep lubricant cycling through the system under conditions where people don't normally use their A/C. Whether you use your A/C or not, at some point you WILL use the defroster.

its just like tires: they too are a "sealed" system.... but we all know that over the course of a year, they too release pressure, needing to be topped off. dose that mean that the tires, valve stems, need to be replaced??? not unless they are deflating weekly.

And that's the reason they use HNBR for A/C system seals and not polyisoprene. Keep in mind as well that not only are tires subject to rolling stresses that move the material around, but the whole tire is, for all intents and purposes, porous rubber. The majority of the A/C system is aluminum hardline with o-ring seals between joints and a couple hoses being the only real places for leaks to form.

A 2-3 year leak in an A/C system IS comparable to your tires deflating weekly when you factor in the dynamic differences in the systems.

I know what you're trying to say, and I can appreciate it, but based on what I've been told by HVAC engineers, it's not correct- an A/C system that discharges enough to need a recharge every 2-3 years is not normal, and needs to be checked for leaks. 2-3 years is not even out of warranty for many vehicles. I'm not an expert on the subject, so I defer to people who are. Most engineers and mechanics will tell you that it is not normal to drop 30% pressure in only 2-3 years, so that's the position I stand by.

[ImStricken06]

I know what you're trying to say, and I can appreciate it, but based on what I've been told by HVAC engineers, it's not correct- an A/C system that discharges enough to need a recharge every 2-3 years is not normal

i never meant discharged, empty. i meant slightly low. 5-10spsi(low side) isnt bad in 2-3 years, and doesnt warrant an expensive diagnostic and job.

i get what you are trying to say, and i agree in many ways; and in an ideal world, no system would loose any pressure- because like you said: "Its sealed" but thats not always reality for many people. sometimes its much more cost effective to simply add a little from a can to boost the system to its optimal pressures.

[zengshengliu]

So today is 70 degree outside, and I finally got a chance to charge my AC system
I look at the chart and it said 70F = 35-40psi
So I connect a manifold gauge to the low side of the system
Pressure reading is 27psi
Here is the confused part:
If I charge the system by gas (meaning holding the can up right), after a while, the compressor will shut down and turn on and off every few seconds (meaning there are air in the system), and the AC will produce only hot (warm) air.
But I searched online and they said you SHOULDN'T charge the system with liquid (can upside down) when the compressor is running, cause it might damage the compressor.
The thing is, if I charge by gas (can up right), the system will take air and I have to take the air out before compressor running again.
If I charge by liquid (can upside down), I might damage the compressor (according to other online source).
What should I do?

[ImStricken06]

that also means TOO MUCH in the system. our car's only require .5lbs and thats it. dont over charge it or you will get the constant frequent cycling. i just had to release some form mine lol. idk why but out cars will always read 25-27 psi and thats it (even if its over charged)

[zengshengliu]

that also means TOO MUCH in the system. our car's only require .5lbs and thats it. dont over charge it or you will get the constant frequent cycling. i just had to release some form mine lol. idk why but out cars will always read 25-27 psi and thats it (even if its over charged)

I see, then I guess my system is fully charged.
Its weird cause you know those gauge that came with the can, they have the temperature listed 70degree F and pressure should be 35-40psi
But I can never get the pressure to above 30 without taking in air

[ImStricken06]

those gauges (i have 2 of them) and neither of them read right on this car. its strange. they all read about 25-27 and never move much. i promise you, you probably have way to much if your system cycles on and off quickly.

[zengshengliu]

those gauges (i have 2 of them) and neither of them read right on this car. its strange. they all read about 25-27 and never move much. i promise you, you probably have way to much if your system cycles on and off quickly.

I think its the system design problem
Today it is hot outside (88F)
And the compressor start shutting down for 5 - 10 minutes before restarting
So I "let some air out" on the low port
And I don't know if it is weather related or not (since its humid outside), the vent start blowing vapor (that I can see)
and at the same time, temperature coming out of the vent start to go up
(But I guess its because of the compressor stopped)