Sport AC recharge cans

hi
any one used these AC recharge cans
im a bit at a loss with info on the can

A/C Doctor

my 2012 RRS says it required 600g of gas in the system
i bought a vacume pump and set of gauges and 4 cans of gas
i bought 4 because on the add it said 170g net for i can and i assumed that was the gas weight
the cans have just arrived
and on the can it says 170g net i put the can on the scales and it reads 278g

but reading the instructions it says
can contains equivalent of 453g of R1231a
so how can i know when i have 600g in system ??

Mike

my understanding is the correct pressure reading is more important than actual weight of the gas - if you top up, its based on pressure on the basis that you don't know how much is already in the system (by weight)

ie - you need 600g in order to achieve the specified pressures

MikeGreg said:

hi
any one used these AC recharge cans
im a bit at a loss with info on the can

A/C Doctor

my 2012 RRS says it required 600g of gas in the system
i bought a vacume pump and set of gauges and 4 cans of gas
i bought 4 because on the add it said 170g net for i can and i assumed that was the gas weight
the cans have just arrived
and on the can it says 170g net i put the can on the scales and it reads 278g

but reading the instructions it says
can contains equivalent of 453g of R1231a
so how can i know when i have 600g in system ??

Mike

Click to expand...

As Kermit say's, the the pressure reading is what matters, with the engine idling and the aircon switched on.

Don't they also require a specific quantity of lubricant?
Not sure how you achieve that without an empty & refill of the system with a weighed quantity of oil to avoid lack of lubricant leading to damaging the pump.

Ratae said:

Don't they also require a specific quantity of lubricant?
Not sure how you achieve that without an empty & refill of the system with a weighed quantity of oil to avoid lack of lubricant leading to damaging the pump.

Click to expand...

just fitted a new compressor come charged with oil
Mike

Ratae said:

Don't they also require a specific quantity of lubricant?
Not sure how you achieve that without an empty & refill of the system with a weighed quantity of oil to avoid lack of lubricant leading to damaging the pump.

Click to expand...

Cans come with oil.

so system is empty
why i bought the vacume pump and not just a top up can

kermit_rr said:

my understanding is the correct pressure reading is more important than actual weight of the gas - if you top up, its based on pressure on the basis that you don't know how much is already in the system (by weight)

ie - you need 600g in order to achieve the specified pressures

Click to expand...

so what would the pressue be cos i cant find any notation regards pressue on by weight
Mike

MikeGreg said:

so what would the pressue be cos i cant find any notation regards pressue on by weight
Mike

Click to expand...

My refill can came with a gauge that showed the correct pressure with coloured zones showing over & under pressure. No idea what the actual pressure is but I can check tomorrow.

I did my Defender few weeks ago with the AC Pro kit.

Totally empty system. Took maybe half the can even though it says online about 700g.

So follow the instructions and it will work

kermit_rr said:

my understanding is the correct pressure reading is more important than actual weight of the gas - if you top up, its based on pressure on the basis that you don't know how much is already in the system (by weight)

ie - you need 600g in order to achieve the specified pressures

Click to expand...

Your understanding is incorrect - refrigerant charge is done solely by weight, pressure varies in a static system dependent upon temperature and by temperature differential when running.
It's possible to achieve the required pressure differential with a minimal charge in the system, but with a reduced cooling efficiency. This is what leads people to say 'it can't be the 'gas' as the pressure is right', when in fact, it is a lack of refrigerant which means it is purely 'gas' in the system, not gas in the low pressure side and liquid in the high pressure side that is the cause of the problem.

Excepting electrical & mechanical faults, the only way to begin diagnosis of air conditioning issues is by recovering, leak checking & recharging with the correct weight of refrigerant.

MikeGreg said:

so system is empty
why i bought the vacume pump and not just a top up can

Click to expand...

If the system is empty, then there is a leak - and it's illegal (and a waste of money) to recharge a system known, or suspected to be leaking. Granted, it's unlikely you'd be caught, but there's sound reasons why it's illegal and there is a £5k statutory fine.
Find the leak first.

AIR CONDITIONING OFF


AIR CONDITIONING ON


Note that the low side pressures (Blue) don't vary much vs. temperature, the top-up cans go on the low side so the gauge is pretty useless in indicating proper function without a corresponding high side gauge.
Then we get into what happens with a malfunctioning system....

If you have gauge set & vacuum pump, then IMHO best thing to do first is to pull a vacuum & see if it holds. Finding leaks at home is harder, as it should be done with nitrogen. UV torch "might" show previous leaks, but only if the system has recently had dye in it.

Graculus said:

Your understanding is incorrect - refrigerant charge is done solely by weight, pressure varies in a static system dependent upon temperature and by temperature differential when running.
It's possible to achieve the required pressure differential with a minimal charge in the system, but with a reduced cooling efficiency. This is what leads people to say 'it can't be the 'gas' as the pressure is right', when in fact, it is a lack of refrigerant which means it is purely 'gas' in the system, not gas in the low pressure side and liquid in the high pressure side that is the cause of the problem.

Excepting electrical & mechanical faults, the only way to begin diagnosis of air conditioning issues is by recovering, leak checking & recharging with the correct weight of refrigerant.

Click to expand...

Thanks for the clarification

There's usually oily spots on the condenser where airborne dirt has stuck to it if the condenser is leaking, the RRS doesn't have rear aircon so that's a whole lot of time saved! other favourite areas are the charge connection valves and the aluminium pipes to the compressor rubbing on hoses until one or both starts to leak...
But yes, UV dye & Nitrogen are the correct way of doing it.

Graculus said:

If the system is empty, then there is a leak - and it's illegal (and a waste of money) to recharge a system known, or suspected to be leaking. Granted, it's unlikely you'd be caught, but there's sound reasons why it's illegal and there is a £5k statutory fine.
Find the leak first.

Click to expand...

the system is empty becauce i just changed the compressor as there was a leak on it very slight but it would have got worse
so it needs to be vacumed to remove the air/condensation

i have done this and it now holds the vacume , so no more leaks
so now needs according to the label on the car 600 g gas

what i cant understand and maybe im wrong!!
on the can it says 170g net weight i put the can on the scales and it reads 278g
so i asume net weight to be the gas and the 278g weight of can and gas
but on the instructions on the can it says
can contains equivatant to 453g of gas

now i know the can is pressured and the gas in side is liquid
but how can 170g of liquid become 453g of gas
weight is weight and surly its only the volume that changes
so how can i tell when it has 600g in system


Mike

The same way an aircon tech. does - use some scales. Digital kitchen scales will do, put the can on it with the hose attached, switch on and charge the system until the weight drops no more, do the same with other cans until the charge weight is 600g is achieved, not forgetting the charge in the hoses - to recover that, with the can & high pressure port isolated, start the engine & turn on the aircon, as the low pressure is the 'suction' port, it will draw any remaining liquid and most of the gas from the hoses.


I'm guessing the weight discrepancies on the can are because what is in the can will be liquid, and they're claiming an equivilent volume of 'gas' which is misleading as refrigerant needs to be liquid and gas within the system in order to work. If you charge by weight, then it will have the correct amount of refrigerant in the system to operate correctly.

It's possible you won't achieve the 600g due to the pressure differential between the small cans and the car once the system has about 30- 50% charge, to overcome this, start the engine & turn on the aircon with the high side port closed, the refrigerant will be drawn in on the low side, fill the remaining weight using this method.

ok
thats how i was looking to do it with scales
but i was confused by the net 170 and the stated 453
so if i go by the 170net i will need 3 and a bit cans i have 4

Mike

The recharge kits & cans etc are expensive - If it's to be a one-off event, surely would have been cheaper to get a garage expert to do the work?
Or do you have repeat work planned?