BXProject

[Vanny]

that pump looks fecking shite, try this!

http://www.ebay.co.uk/itm/Robinair-1550 ... 588fdd7c78" onclick="window.open(this.href);return false;

I can only do a fairly light job of cleaning the oil out because, as i've mentioned, I DONT HAVE A CHARGE RIG!!!! So there is fuck all i can do!

Oil, well there are a number of grades. I would recommend ND8 oil, its expensive for a reason, if you can even find it. I've managed to find it before though.

[Way2go]

clean all the old oil out, and put some new oil in. What oil, and how much do I buy?

PAG oil isn't it?

http://www.autofrost.com/hotshot/index.html

Also essential that a thorough job is needed as the article says even minute amounts of the old stuff and pipe contaminants will cause the PAG oil to break down within a month!

Can this be done DIY or is some kind of professional system flush needed? Can the compressor be drained and flushed on the car or is removal, strip and clean needed here too?

I've bought a new dryer for mine too but not fitted. The system has not yet been opened and I don't want to do that until everything is readily to hand and procedure known.

Alan Smith used to suggest R134a changes from R12 could be made by attention to the green 'o' rings, empty compressor & refill with PAG oil and a vac down with an old fridge compressor but neither he nor anyone else has come up with a good and full step by step instruction procedure. (Oh yes, AS used to stress special importance on changing the dryer too )

Maybe Vanny can write up a proper procedure for us here with all the i's dotted and the t's crossed?

[smiffy]

That would be great if he could.
I've been on the ebay shop autocool, and there are all sorts of things there that sound like they'd be usefull, but unless I knew what I was buying, or if I needed it, I guess I'd be wasting A LOT OF MONEY. Things like charge hoses (red, blue, or yellow...what are the different colours for), adaptor kits, and such....they even have a R12 to R134 kit, but i'm not entirely sure this would be for me.
There are other vacuum pumps on ebey too, and in this country, so postage would be a whole lot less!
As I've said elsewhere, I've never had anything to do with air-con before, so I just don't know what I'm doing!

[Philhod]

Yes. Apart from knowing the technology ie how it works, I have no experience of the units at all. Recently Gregzee bent his Corsa slightly but punctured the a/c rad.
When I disconnected it I heard all the gas exit. I have physically stuck it all back together again
but have no idea what to do next, to get it working. Note:- I'm pretty good at following detailed instructions that also tell me what PAG or ND8 is.

[Vanny]

fuck me, this would take some time to give sufficient detail. With the correct hardware its a doddle. Let me try to address the basics;

PAG (Polyalkylene Glycol) (mostly) lubrication oil is compatible with HFC's (HydroFlouroCarbon i think) ie R134a (currently fitted to new EU cars and used since the early 90's) or R1234yf (There are about 10 cars on the road with it, but it becomes EU law next year). There are a huge range of different manufacturers of compressors, and each one recommends there own brand. Denso compressors use ND8 (Nippon Denso formula for R134a and ND12 for R1234fy. To my knowledge the ND8 is the only oil good enough to be acceptable in other brands, specifically Sanded compressors, which is what we have in our BX's.

Hoses and colours and guages. At a basic level you need three hoses and two guages (you can get away with 2 hoses but its difficult). Red is high pressure (and requires a high pressure guage), Blue is low pressure (and requires a high pressure guage) and yellow is for refrigerant.

Basically you vac down through the low pressure side (which naturally draws the oil upstream of the compressor), then you vac down the high side (they can act as completely different systems), then you refil, by WEIGHT, on the high side. Hmmm, i'll need to edit this later!

To RECHARGE you need a bottle of R134a gas, a waste gas store, a suitable recovery unit, a vac pump, three hoses, a set of guages and a set of very accurate, and expensive scales. At the bare minimum. If you want to do the best job you'll need a TORR guage, gas analyser and some other expensive bits and bobs.

To flush the oil out of the pump you do only need to flush it, under high pressure, with the correct oil, for quite some time. Its not something i'd recommend doing on the bench without some decent equipment.

This should give you enough to start googling. I do have some training docs which i will look to scanning up.

[mat_the_cat]

a waste gas store

= the atmosphere?

When I got mine charged up I initially went to a place in Gloucester that seemed very clued up. They recommended vaccing it down overnight as it had been open (with the leaking condensor) for quite a while. They also said that they wouldn't bother changing the compressor oil, just put in a drop in R12 refrigerant, although I changed all the O rings anyway. However by the time I'd found and fitted the new condensor I had moved to Wales and found a local place that would refill with RS24. They only vacced it down for about 30 minutes or so (despite me saying about the system being open) and filled it without (that I could see) weighing it at all. They just connected the bottles and filled it with the system running and at some point, possibly going from a pressure gauge reading one guy said "That'll do".

That said, I put a new reciever drier on just before they vacced it down, and it has worked acceptably for the 5 years since. The only problems I've had are a failed control slider (thanks to Chris for the replacement) and the radiator fans coming on full (when in France during 40°C+ heat) briefly, I suspect due to overpressure.

[Vanny]

the atmosphere?

Well its like this, 600g of HFC is not going to make fuckk all difference to anything. If 1000 people do that (including crashes etc), its going to be noticed, if everyone starts doing it, where fucked!

Seriously though. Water boils at what 99.6c at 1 bar atmospheric pressure, show where around that. Without having my carno maps in front of me, if you vacuum it down to 2TORR, then the flash point is around 5c. Most garages/workshops etc are 16c + so by vacuuming down to 2TORR ALL moisture will boil off. And unless you've poured a bucket of water into it, most moisture will be gone in 15 minutes and totally gone at 30 minutes.

This is why you need a good vacuum pump. Most will reach 1 TORR without to much bother, quite a lot will reach 1.5TORR given some time, but a decent one will manage 2 TORR bloody sharpish. Vacuuming over night iether means they dont pay electricity, are fastidious in there approach, don't know what there doing, or have old equipment. Though if its that slow to pull a vacuum, it wont make 2TORR.

You CAN recharge by watching the pressure guages, with the system running, you slowly eak the gas in and eventually the system gets to a bit of an equilibrium. But this always results in overcharge (lesser of two evils) and reduces efficiency.

[Philhod]

Sounds complicated for some reason.

As I remember, on building units, you have 5 main components. A motor/ compression pump, a condenser, Drier, an Oriface tube and lastly an evaporator.
I only watched them and all they seemed to do was disconect the drier and leave it for an 1/2 an hour reconnect it then re charge from pressurised cans, through a valve in the pump.
They used no guages that I could see or vacuum units and it all seemed to work when switched on.
This was back in the 70's, in the middle east, if it makes any difference, at +40 degrees and about 3% humidity.

[Vanny]

if it makes any difference, at +40 degrees and about 3% humidity.

Well, yeah, the moisture in the system open will be very close to ZERO!

Orifice tube, sounds more like the dark ages than the 70's. Cars havent had them for a long long long time. Though i suspect building HVACs will still have them as they are pretty bomb proof.

If you have a charge station, you open the low side and press go. Give it 45 minutes, come back, close the low side, open the high side and press go. Give it another 15 minutes, disconnect hoses, drive off. Sound a bit simpler?

[Way2go]

There's a recent WikiHow on this:

http://www.wikihow.com/Fix-Your-Car%27s-Air-Conditioner

I'm not sure if it says it in the article but I remember that Smiffy and I also need to fit special pipe adaptors to the schrader valves of the BX in order to facilitate coupling to the R134a charge rigs.

[docchevron132]

or, I'll get Mannies mate that does nothing but AC to vac it and check it?

[smiffy]

ok, yes please!

[Philhod]

Sounds a lot better that Vanny.
Mind you, my description of what they did is working from memory of just watching 35 years ago!!! They may have done other things that I have conveniently forgotten

[mat_the_cat]

You CAN recharge by watching the pressure guages, with the system running, you slowly eak the gas in and eventually the system gets to a bit of an equilibrium. But this always results in overcharge (lesser of two evils) and reduces efficiency.

That fits with my overpressure in extreme heat then, and the fact that the vent temperature is 7°C which I guess is a little on the high side?

[Vanny]

W2g, the adapters are £2.50, so nothing much to worry about.

Doc, this would be a very good idea. AC techs who have a big charge trolley are shit, those with individual pumps, scales etc are ok, though with a canister of OFN are GOOD!

Mat, 7dgC does sound a little high, but i suspect that is measured at the outlet, in which case it might not be so bad. The BX has thin, soft blow moulded ducts which pick up a lot of heat AND induce a lot of system noise, so it might just be that you can't get any better. But i would home for better tbh. Oh it might also be a badly tuned TXV, they tend to be worse on retro fit systems. Annoyingly its a rather lengthy procedure to determin the spring tightness.