repaircon

tomsheppard · Post by **tomsheppard** » 11 Mar 2004, 13:56

Has anybody experience with aluminium solder? I'm considering the repair of an aircon condenser with a tiny pinhole from a stone.
I have been told that if the system is open for more than a couple of hours, the receiver/ dryer will need replacing. I'd like to know why and why it couldn't be rejuvenated.

Kowalski · Post by **Kowalski** » 11 Mar 2004, 14:41

The dryer has to be replaced when it becomes saturated with water. If you open the system to atmosphere the dryer will absorb all the moisture it can since it is rather hydroscopic.

AndersDK · Post by **AndersDK** » 11 Mar 2004, 15:00

To solder on aluminium - you need a special solder flux and a special solder mix.
The idea is to avoid the solder point is allowed to reach free air - as any cleaned aluminium INSTANTLY is covered with a fresh layer of aluminium oxide - which is impossible to solder on.
But as Kowalski writes - it's already too late. Once water has come into the dryer side - it's aircon heaven. No one will warrant a repair/refill of your aircon system.

tomsheppard · Post by **tomsheppard** » 11 Mar 2004, 15:05

So If the dryer was replaced, I'd be ok?

Post by **RichardW** » 11 Mar 2004, 15:39

If you can repair the condenser and get a satisfactory pressure test on it, I can't see a reason why an aircon tradesman shouldn't be able to change the dryer and refill the system. FWIW I would think the dryer should be rechargeable, say by blowing hot dry nitrogen through it, but the manufacturers may have used some sort of drying agent that will not respond to regeneration - if you had the necessary you could give it a try and see if the dryer changes colour back to 'dry'.

tomsheppard · Post by **tomsheppard** » 11 Mar 2004, 15:45

Thank you everybody. Due to my other half's medical condition, an air conditioned car is a necessity and I like BXs So I bought a petrol engined car with Aircon and I am faced with converting the TZDT. This is going to involve sump swaps and dashboard out to change the heater. It is all a lot of work to do but that's the price of love. If anybody has ever done this before,I'd appreciate any advice thats going!

Post by **Jon** » 11 Mar 2004, 18:08

AlanS, our Air conned BX owning bloke should be able to give some advice on this one?

1Dude · Post by **1Dude** » 12 Mar 2004, 15:50

I am planning to do a similar aircon instal in a TZD.It is a basic plumbing job really. The part which may be a bit tricky is getting the radiator fans to work properly and independently for both aircon condenser cooling and normal two speed engine cooling too (important on the turbo).
If you get yourself the appropriate wiring diagrams then it should be achievable.
There is someone on one of the forums who has allegedly actually done this job a few years back.I will try and look it up if you feel you want to touch base with someone with the appropriate experience.

1Dude · Post by **1Dude** » 12 Mar 2004, 15:56

As far as I know the main purpose of regassing the aircon on a regular basis is to REMOVE the moisture from the refrigerant.
My local aircon regasser does not renew the drier receiver as he says its gets dried out during the process of regassing..........Hope this helps.

Kowalski · Post by **Kowalski** » 12 Mar 2004, 16:50

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by tomsheppard

So If the dryer was replaced, I'd be ok?
<hr height="1" noshade id="quote"></blockquote id="quote">
Yes, as long as the system was sealed or contained excessive amounts of water (i.e. liquid rather than vapour). If it isn't sealed the dryer would end up wet again.

alan s · Post by **alan s** » 12 Mar 2004, 16:51

Unless the system is totally devoid of all gas & has been in a wet environment or alternatively has been run until every last drop of refrigerant has been lost, it's highly unlikely that too much moisture has got in it.
However, I wouldn't even try to solder it as for starters you'll have to remove it from the car at which time it will get contaminated with moisture. The reason I say it has to be removed is for access & also if still connected, the gas in teh system will expand with heat & blow bubbles/holes in your weld/solder job.
Another good reason would be that the condensor operates on the high pressure side of the system hence your solder/weld job has to be able to withstand pressures of at least 125 psi & up to 300 psi in extreme conditions; ever heard a tyre blow at 30psi...that's a fair comparison of what it's holding back.
I know this is an extreme method but unfortunately probably will work out the cheapest in the long haul; new condensor, new dryer and regas.
With the labour involved & the potential to drop the gas charge in a very short period of time if the wels/solder doesn't hold, as I say, possibly your cheapest & best option I'm sorry to say.
If I thought your suggestion had a better than 50% of working, I'd be the first to suggest it. You could be lucky but it's a big gamble.
Alan S

tomsheppard · Post by **tomsheppard** » 12 Mar 2004, 16:53

The drier/ receiver isn't unduly expensive. What would help would be to know the differences between the TZI condenser and the TZD. I wouldn't mind a little adaptation to save the cost of a new condenser I suspect that it is a radiator clearance issue. The oil in the system picks up the moisture which, I am told is what kills the drier but then a friend with an Espace had a holed condenser for years and didn't need a new drier when the man fixed it for him. His aircon works just beautifully, I shiver at the thought of it.

alan s · Post by **alan s** » 12 Mar 2004, 17:19

It basically works on width X height X thickness (number of layers of pipes for the want of a better word) in other words volume & surface area. Providing the compressor & other components are about the same size, it should work if it fits.
I had tradesmen MIG weld evaporators on light commercial applications as well as domestic jobs that still leaked slightly afterwards to give you an idea of the job it is to seal them by repairing & that side of things works on about 0 - 12 psi.
Refrigeration oil is hygroscopic there's no argument about that but a pin head of moisture can stop a supermarket freezer. Moisture can get into & circulate with the oil but then freezes as it boils off through the oriface of the TX valve & as it expands when it freezes, then it simply blocks off the gas flow.
Moisture can be admited to the system in the humidity in the air & normally, when a leak is sprung, the moisture forms inside the system whilst it's cold in exactly the same way as it forms on the outside of the pipes in the freezer when it is operating normally due to contamination by air containing humidity.
In the event of a hole being punched into a pipe, it often duplicates the action of the TX valve as the gas in liquid form spurts out of the hole & creates frost as it goes & hence creates the moisture that causes all the trouble.
Alan S

tomsheppard · Post by **tomsheppard** » 12 Mar 2004, 17:57

Thanks Alan, that makes a lot of sense. I'll change the drier as a matter of course. I'll need to change the compressor seals as well to use R134 won't I? as far as I know, this is an old R12 system. Just for curiosity's sake is there any difference in the efficiency of the two refrigerants?

alan s · Post by **alan s** » 13 Mar 2004, 02:29

Tom,
The R134a runs at higher pressures than the old R12 did.
An alternative we have out here is MP52 which is a gas that "goes over" R12 & is less expensive as it needs less work to convert to & runs at pressures similar to the old 12.
It has a limited lifespan before they phase it out (I think it's what's known as market monopoly) but we are talking a number of yearsso it's well worth the effort to investigate.
Alan S
P.S. If an Air/con guy looks all dumb about it, it's possibly not because he doesn't know about it but more a likelehood of wondering where you heard about it.[:D]
Alan S [;)]