A/C Recovery Recharge Machine

[steelcityuk]

Hi All,

Ihope I've got this in the right section, if not please move - thanks Mods.

In the hope of fixing the A/C on the SED I decided it maybe better to get the tools together to allow me to do the work myself, that way if it took multiple attempts to find leaks I wasn't going to be paying over and over again not to mention having to take the car in to be fixed. So I bought a A/C recovery and recharge machine via Ebay.

It's an Ariazone 1001 with Recovery Plus module.


I'm hoping that using the machine I can give the XMs A/C a thorough service. The hope is that once I prove that everything's intact with no leaks I can empty and replace the compressor oil, flush the system, replace the receiver drier and recharge the system. I was wondering about the use of Propane for testing purposes, that it to say on the driveway pressure testing, usually A/C systems are pressure tested with Oxygen free Nitrogen but Propane is easier to get hold of and should be safe for such use.

The cost of R134a had really shot up judging by current prices. I've read that this is because of the prices and availability of feedstocks to make the gas.

Steve.

[addo]

Was it 'spensive?

[MJM]

A couple of things spring to mind.
What do you propose to flush the system with? (just curious)
Will propane have an adverse effect on any rubber seals or oil in the system?
Will a vacuum decay test be good enough?

If you do use propane then a fag lighter or a match will pinpoint any minute leaks.

[addo]

Propane doesn't hurt the O-rings. Also it's so strongly odorised that a tiny amount can be smelt by a healthy nose.

FWIW brake cleaner does a nice job on flushing. Bit dear for the purpose, though!

[steelcityuk]

Hi,

The machine cost £240 so probably the same price as a quality vacuum pump.

Initial recovery of the system proved it had a major leak so the first test was done with compressed air. The condenser has a big leak. Following the replacement of this I'll try vacuum testing again for more leaks before I pressure test with butane. If it holds pressure I'll remove the compressor to drain it's oil and flush the system. Rebuild and test again using butane through a drier. Then vacuum out and fill with R134a.

Brake cleaner can be bought for less than £10 for 5ltrs so this maybe the method of choice.

Steve.

[steelcityuk]

On Saturday I stripped down the XMs front end and removed the condenser, it
looked old but not a complete mess. Another pressure test confirmed that there
was multiple pin holes, so that's the end of that.

The system is a R12 type that had been 'converted' to R134a, I say 'converted'
but apart from the changing the filling ports there's no way I'll know if it was
done correctly, such as removing the expansion valve and flushing the system,
etc.

A new condenser and drier were ordered, shopping around got the price down to
just under £110, as for the quality at this price we'll just have to see.

The next job was to remove the compressor, make sure it wasn't seized, remove
and replace the oil with fresh PAG. Well it wasn't seized but it didn't have any
compression and there wasn't any oil to drain. I added some oil to see if this
improved the compression, it didn't. Stripping off the head revealed no visible
problems, no rust, no cracks, no bent valves, just dark grime. All the pistons
were intact and moved in the correct fashion, however placing a palm over each
individual cylinder indicated that only two of the seven cylinders had decent
compression, non of the cylinder bores looked worn so it's probably the piston
seals that are knackered. Taking the front off the compressor showed that there
was no obvious damage but it looked like it hadn't seen any action in a long
time. The bearing races and swash plate were covered in dark grime, removing the
piston assembly showed that the piston seals had failed.

I've decided to go with a replacement compressor from the local breakers, the
original compressor is a Sanden SD-709 (7 pistons, 0.9 cu inch displacement) R12
type. It's equivalent R134 type is a SD7H15, these seem to have been fitted on
all sorts of European cars in the mid 90s so should be plentiful. Alternatively
a variable type such as a Sanden SD7V16 can be used and 'converted' for use in
place of the SD-709. Either way the head will have to be swapped over.

Steve.

[addo]

No oil plus dark grime suggests to me, the front seal failed first - letting much oil escape. It's advisable to replace this seal at major services (like that you are undertaking now).

[steelcityuk]

I think you maybe right Addo the felt in the nose was sodden.

Currently I'm trying to find a compressor that is a virtual drop in replacement. Using a Sanden SD7V16 isn't so straightforward because the head cover is different and so I can't swap the one from the SD-709 which means I'd have to get the hoses modfied or have complete replacements made - this would be the better option and should have less likelyhood of leaking.

The new condenser and drier for the XM. The quality seems fine.

More to follow.

Steve.

[DickieG]

Photo link isn't working.

[steelcityuk]

Currently can't get the photo to show but the link works elsewhere. I'll try again later.

[addo]

In 4-pot petrol cars a leaky HP pump bonds grit onto the compressor shaft in the seal area behind its clutch.

Also remembered a comment from my AC "expert" that the R12 pressostat was better for converted systems than an official R134A replacement. The medium pressure is different; I think he felt it taxed the compressor less by starting sooner. This may not tally with book theory but I defer to six days a week, twenty years' experience.

He also is a big fan of the thinner wall Galaxy hose when space is tight, although it requires different fittings.

[steelcityuk]

That sounds like good advice to me Addo.

Currently I'm looking at a compressor that's meant to drive refrigeration units so it has beefed up swash plate, bearings and seals but the best part is that it is based on the SD709 so it could be a drop in replacement. I've sent off an email or two to local flexible hose companies to see what they offer.

Steve.

[steelcityuk]

The new compressor arrived. The electric clutch, pulley and head were swapped over. I charged it with 135g of mineral oil and fitted it.

I can't get my photobucket images to show here so if you really want to see them you'll have to checkout my postings elsewhere.

Sorry.

Steve.

[steelcityuk]

Following advice given, I 'filled' the system with Butane/Propane mix using
blow torch cartridges via a in-line dryer. The pressure switch was bridged out
and the engine running. Because of the method of filling I could only keep my
high pressure hose connected so I kept 'feel' testing the system. Sure enough
the compressor side of the condensor got hot and the receiver/drier side of the
condensor was warm. The output from the evaporator was cold. Every so often I
stopped filling and connected up the low pressure hose to take a reading. The
temperature outside was only approx 7 C so not ideal testing temperatures but
turning off the A/C misted up the windscreen and turning it back on again
cleared the windscreen. The system was charged with approx 500g of the mix.

A/C turned off
http://i1224.photobucket.com/albums/ee3 ... 3e3c35.jpg" onclick="window.open(this.href);return false;

A/C turned on
http://i1224.photobucket.com/albums/ee3 ... c64328.jpg" onclick="window.open(this.href);return false;

Now that the system is under pressure I intend to keep checking for leaks whilst
I rebuild the front of the car and attend to some other jobs. Also I need to
make some decisions about what to use as a permanent charge. R600a is easy
enough to get hold of but R290a isn't or do I just buy off the shelf drop in
replacements that I reckon must be this mix?

Steve.

[vanny]

Have you considered buying reclaimed R134a? You'll have to search for it, but basically there are companies that buy in old 'waste' cylinders, filter the moisture and dirt and sell it on. The risk is that you will end up with R134a with a drop of R12, not a problem if you use a multi purpose PAG oil though.