My Citroen XM 3.0 PR-Vestige

[Dean]

Interesting.
The Citroen recommendation to use R134a goes back at least to 2001, the date of theI have, so not a 'recent' specification.
I would be choosing a real expert, rather than a monkey, as you say.
The correct oil, and the correct amount of it, is crucial, as is the right amount of refrigerant.
Not sure whether the 2.0 system is less powerful than the 2.5, but our 2.5 AC is capable of freezing your nuts off, even when the outside temp is 40C - and with R134a.
I think I read that the original XM climate system was designed to achieve the chosen cabin temperature at any outside temp between -50 and +50C, but maybe, in 1989, that was with R12.

Whilst surfing the web I read the R12 was blended in 1920 something, R134 was brought in to existence five years later but wasn't widely used in cars until 1992 due to environmental concerns, some american states are considering banning 134 now apparently .

The more I read about R12a (propane) the more I think its the way to go, lower operating pressure, better cooling, better lube distribution and much lower pump load, its just finding someone who can do it over here.
http://www.redtek.com/win_12a_prod.html" onclick="window.open(this.href);return false;

D

[Dean]

Another 150miles on the xm so far this week and spot on, the abs has been very happy with not a single blink or logged fault, engine starts and runs perfectly with no issues, interestingly the new fuel pump has done 3 very noticeable things, its stopped vapour lock so she starts on the button from hot, which is helpful, its improved mid range torque so it will go up hills in 4th fairly easily now and its smoothed out down shifts on a trailing throttle so the gearbox is spot on now.

Getting a lot off attention this week too, got a thumbs up from a guy in a TVR Mon and this evening from a S3 driver, get flashed quite a bit by men with beards on old English tat, I went and quoted for a guy who has moved over from France with his family and took the xm out, I thought he was going to melt when he saw it but wasn't complimentary of the engine. Said I need 3 litres, or 4.

Stopped in a local garage on the way home and the guys from the workshop came out for a look, started talking and we came to the subject of air con, seems they will flush, VAC and charge with R12a, I just need to buy the refrigerant and the type of oil I want as they only use R134a with pag and don't get much R12 recovered these days, got to find some mineral oil too as I don't want to use pag oil if I can help it, R12a is compatible with both types though.

So, all is going well, next stop is my paint man, I've got 5 years of favours owing!

D

[White Exec]

If R12a is indeed Propane, I think you should read this...
http://www.aa1car.com/library/tr497.htm
It specifically warns about the dangers of filling vehicle AC systems with inflammables like propane.

R134a ban? For sure, all such volatile organic liquids will get banned at some point, and mixtures and blends of these only compound the recy/collection/environmental problems. Until Peltier or similar makes this kind of refrigeration obsolete, I suppose we're stuck with it.

Thought: If the limiting factor of R134a on older XMs is the smaller condenser, then why not replace it with the full size item from the later cars? R134a plus the appropriate oil is both recommended and approved, and easily available, so it seems not unwise to use it.

[Dean]

Yes Chris I've seen that, its not illegal in this country, in fact perfectly legal, R12a is not a CFC, not carcenagen either.
The reason I want R12a Is because it halves the load on the compressor, works better and can be used with any lubricant and a far wider range of seal materials, I spent most of the weekend researching and after my chat with the ac guy today its made my mind up.

There is the explosive issue but to be fair I spent 2 years driving a lorry delivering propane and butane, I drive a car that has 90ltrs of petrol in a glorified plastics box that the exhaust pipe runs straight through and I keep a blow torch in my truck with me at all times which has 3 times as much propane in it as the AC system will have in it with a far greater risk of leakage, and that's before we talk LPG conversions. R12a needs roughly half the charge weight of 134 so we are talking about 300 ish grams and every positive testimonial I've read has been from someone who has done it, every negative one has been from people who have not.

The condenser upgrade would fit with modifications to the front panel and a different drier, and possibly hoses, and to do it right ( depending on who you talk to) a new pump but that's a lot of effort to go through when the information suggests I could keep what I've got and end up with a far more efficient (certainly in terms of engine loading) ac system.

Time will tell

D

[White Exec]

I can tell you're convinced on this one! Just wonder why the auto industry doesn't use it too.

[Dean]

At a guess i would say because although its more environmentaly friendly, a few country's (certainly a few American states) do not allow hydrocarbon refridgerants and there would have to be two different systems, also maybe safety reasons, the same sort of safety rules that killed Citroens hydraulics as i think all critical systems being run by one pump was banned wasnt it? maybe issues with inflammables escape into the cabin area in the event of a serious accident?

I shall gladly be test for this one, it can only go one of two ways!

D

[xmexclusive]

I seem to remember Shane in Aus being a propane user for his aircon.
All fully reported but not sure which club site, suspect it will be the original.

John

[Dean]

Now you mention it i think your right, i will trawl back on that site and see if i can find it, see what he has to say about it, im sure if it was rubbish Shane would be the first to say.

D

[Dean]

A little fun and games this evening, changed the gearbox oil again and performed a little modification to make my life easier when filling the box, I count that a success!

Unfortunately while going out for a drive to get the oil moving ready for a second change of fluid I had an overheat warning flash, the orange thermometer with the arrow on it, temp read normal and no low coolant so I carried on, half a mile up the road and all hell breaks loose, fans come on and off running at full chat, relays buzzing under the glovebox and all three relays on the n/s slam panel chattering away like mad with the cases lighting up with blue flashes. I quick inspection found that wiggling the main harness plug under the lhm tank that i didnt re wire brings warning lights on and the fans accompanied by lots of relay chattering all over the car, that part of the harness could do with replacing before she goes out again I think!

[White Exec]

The 3 fan relays under the slam panel are handling one hell of a current between them (each fan is rated 310W iirc, that is c.25amp apiece, ie 50amp in total. For the relays to cope with this they MUST get a nice clean switching instruction from the ecu/thermoswitch, and no mucking about or intermittent coil feeds. Otherwise, donner und blitzen will result.

The resulting current surges will probably be enough to throw the electrics and alternator output into disarray, so all sorts of other things may go unstable......like other relays starting to chatter, and lights flickering.

I bet it's just one dodgy connection somewhere.