Air con not working - re-gas required?

EdGasket

B00st wrote: »

Though you have no idea how much gas is already present in the system so could potentially overfill it, cannot check for leaks and have no way of evacuating any air that will also be present in the system if the gas level is low.

The cans are not powerful enough to overfill a system and one can will certainly not be enough to cause damage. In fact the pressure in a can is just about enough to lift the pressure to the bottom of the 'filled' section on the dials I have.

snowcat75

EdGasket wrote: »

There weren't any growing last time I looked, just a fair amount of moss

On a more serious note, while all of what you say is valid, people like me on a budget and with an old car aren't interested in spending £££'s on getting problems with air-con diagnosed and fixed. We just want a cheap refill to get cold air through the summer. I have used a can of EZ chill on the Merc which has lasted into its second season and a can per season on my Hyundai which lasts most of the summer. If it gets to the point where a top-up/refill doesn't work, then I'll just open the window instead.

Thing is though if you take it to someone who knows/can be bothered it will cost less than those cans. To take a quick look at a system, I don't charge, never have, It takes a minute to put a set of manifold gauges on, and Its rare that it ever takes more than a few minutes to find the fault, If im going to re-gas a system that I know has lost gas nitrogen goes in, If it pressure tests without any creep on the gauge then chances are it will hold gas for the summer, job done, all for the kings ransom of £50, which I think makes £40 for a can with a sniff of gas look !!!! 'in expensive.


I only started doing A/C systems because I ran plant of my own, and needed to repair systems PDQ before the revolt from operators in the summer.


Someone who knows what there doing will never be wanting to charge or sell £££ of un-necessary parts of labour.

EdGasket wrote: »

The cans are not powerful enough to overfill a system and one can will certainly not be enough to cause damage. In fact the pressure in a can is just about enough to lift the pressure to the bottom of the 'filled' section on the dials I have.

That's not true, If a system has a full charge and its something like a KA with only a 500grm charge even a tiny extra 100gms has just put a 20% overcharge in.


As I stated gas pressures are not a constant (basic physics) relative pressures change with temperature, so a system that shows normal working pressures on a 18C day say 2bar on the low and 5 on the high, could be 3bar on the low and 7bar on a 25C day, There are calculations that can be made using comparative slides, but there open to such error and assumptions that the only time they are used is in a classroom.


The only way to measure how much gas is in a system and if its under or overcharged is to empty the system, vacuum and re-gas by weight, and that is a fact.


An overcharged system should protect itself via the HP switch in the same way it does when its low on gas with the LP switch, however and iv seen this with overcharged systems the compressor cycles and typically jumps between 7-15bar almost twice working pressure before the switch trips it, this can blow the manifold gasket pipes, or even the worst iv seen overheated a compressor sized it up, and then destroyed the water pump when the belt disintegrated.

EdGasket

With the £10 back on the can it's £30 a fill and last time I got 3 cans for two so even cheaper (not sure if I get £10 back on the free can as well) Plus saving booking in and driving to somewhere to get it done. Plus, well I just like to do what jobs I can myself; it's satisfying.

snowcat75

EdGasket wrote: »

With the £10 back on the can it's £30 a fill and last time I got 3 cans for two so even cheaper (not sure if I get £10 back on the free can as well) Plus saving booking in and driving to somewhere to get it done. Plus, well I just like to do what jobs I can myself; it's satisfying.

but how much weight of gas does one of those cans contain? very little I suspect, so it is whatever way you look at it is an expensive way of buying gas.


Gas bought in a cylinder is under £8 per KG.


Im all for doing jobs myself spent years building everything from CNC machines to rodding cars, and have run plenty of pickups and trucks to galactic millage.


My thoughts always are to do the job properly, so personally Id buy a cylinder of gas, some manifold gauges, and a S/H vacuum pump, gas can be weighed on kitchen scales, total set up no more than £150, do a couple of neighbours cars and money back. but that's just my perspective on jobs.

EdGasket

snowcat75 wrote: »

but how much weight of gas does one of those cans contain? very little I suspect, so it is whatever way you look at it is an expensive way of buying gas.

It says 18oz so about 500gm; not enough to overfill but enough to get a non-working system working again. Personally I don't want £150 of air-con kit to store and neither do I want to be involved with neighbour's cars but each to their own.

Plenty of happy users of EZ chill:
http://www.halfords.com/motoring-travel/engine-oils-fluids/air-conditioning-recharge-supplies/ez-chill-auto-air-conditioning-recharge#tab3

bigjl

Iceweasel wrote: »

Every car I've had for the last 30 odd years has had air-con.

I leave it turned on all the time - Summer and Winter - never needed a re-gas and never had a problem.

Unfortunately many people still think that air-conditioning is for cooling only - forgetting that it dries the air and keeps condensation down - I run mine along with the heating to get the best effect.

Use it or lose it, as they say.

My dad did exactly the same. And never had a car need a regas either.

It does depends on circumstance and mileage though.

As running AC makes a difference to your fuel economy.

So if you do higher miles running it all year becomes costly.

My car will average 32mpg in mixed running with AC off and drops to 28mpg with it on.

bigjl

B00st wrote: »

Though you have no idea how much gas is already present in the system so could potentially overfill it, cannot check for leaks and have no way of evacuating any air that will also be present in the system if the gas level is low.

There is a gauge on the can.

Have used them a few times.

And you have a range to use for the temperature. So I don't see how you could damage anything unless you fail to read the instructions and just keep filling.

Often AC won't kick in if there is insufficient gas in the system, to prevent damage to the compressor I think.

Not sure if that applies to all cars though.