| Author | Message | |||
     John Aravanis Experienced User Username: krug300 Post Number: 23 Registered: 2-2005 |
I need some advice regarding the conversion of my SRH8685's A/C refrigerant from R12 to 134. I want to keep the very tidy engine bay original so the throttle suction valve and Frigidaire compressor must stay. I read that the addition of PAG oil and an emulsifier plus the replacement of the receiver/drier will make the system ready for R134. What's your experience on this? Any help will be appreciated because R12 is now non existent in Greece (and my system needs an annual charge of R12. I did replace the suction valve diaphragm last week) John | |||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1098 Registered: 4-2003 |
John, Your summary is spot on. There is nothing to worry about here. I had this done over 16 years ago on '72 SBH13247. Our local air conditioning shop did the job at a cost of no more than a normal compressor service (as opposed to a partial recharge). The receiver/dryer element is a common type, as is the PAG oil, so the Crewe part numbers in the attachment may be largely ignored. The charge required, at around 1kg, is about 30% less than with R12. Your shop will know all this. Your need for an annual recharge is a shame. Given that you have a new suction throttling valve, the shop needs to do a few more tests. The leak could be anywhere. As a guide, about ten years ago I replaced the suction throttling valve (I had not seen the bulletin to delete it in favour of cycling the compressor), one hose and the o-ring on the cap at the non-drive end of the compressor (in-situ). All had very slight leaks and were very difficult to detect. Apart from the valve itself, the costs were negligible: the shop made the hose to pattern. It has not needed a recharge since. Maybe you would be wise to replace both hoses and the compressor o-ring and try it out. RT.
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| John Aravanis Experienced User Username: krug300 Post Number: 24 Registered: 2-2005 |
Good to hear from you Richard, the diaphragm was replaced last week during the annual service. The shop charged the system (they claimed with R12 at a cost of 80 euros) but it doesn't produce COLD air, and there are alot of bubbles visible through the sight glass. One of the many things I am proud of my Shadow is (was) the ICE COLD air conditioning. Since no one will attempt to "mess" with the Shadow's A/C system in depth, I must take the "responsibility". I spoke with autokool.co.uk and they can send me the oil charge can, plus the new valve fittings etc. I asked if they were familiar with the Freeze 12 direct replacement that is readily available in the States and they told me that they carry it. I therefore have to choose to either pull a good vacuum, check for leaks (the points you mentioned) and simply refill with Freeze 12, or install the new receiver/drier I also recently purchased (did you know there is no sight glass on the new units?) and go the R134 way. With the winter around the corner I am tempted to recharge with Freeze 12 and wait until next spring. If there is a loss of refrigerant I can then proceed with the conversion (there is also a leak stopper that I can introduce to the system). Thanks for your assistance. Regards, John | |||
| Larry Halpert Prolific User Username: larry_halpert Post Number: 95 Registered: 9-2003 |
Not to divert the subject, as I stick with R12 because it is readily available at low cost internationally through ebay. BUT from my research I would definitely stay away from leak stopper as that will gum up, as well as clog small evaporator and expansion valve passages. (No matter what they say about "rejuvinating seals") Taking out the evaporator is sorta, kinda a itty bitty difficult job, not to mention trying to get that stuff out of the rest of the system. Larry | |||
| David Gore Moderator Username: david_gore Post Number: 658 Registered: 4-2003 |
Welcome back John, When your system was recharged with the R134, did the shop actually weigh the charge or just pull it in with system vacuum? The bubbles in the sight glass are symptomatic of insufficient gas charge. It is my recollection that instructions for the conversion always emphasised the importance of weighing the charge and not using system gauge readings to determine the "correct" charge - If my memory is correct, the R134 has a higher "head pressure" than R12 to give the same heat transfer capacity. For Larry, Are you aware that R12 is a banned refrigerant due to its effect on the ozone layer and levels of UV radiation [very important to those of us who live in Australia due to our proximity to the actual hole in the Earth's ozone layer and our resulting high incidence of skin cancer and melanoma]. Most of the R12 being sold now is recycled gas recovered from decommissioned A/C & refrigeration equipment which should have been quarantined for safe disposal. These products are often heavily contaminated so the actual R12 content is much less than that of the original OEM product. Please do not support the environmental vandals of this world whose greed surpasses their consideration of others who have to endure the risk of cancer due to the effects of the product on the world we all share. | |||
| Larry Halpert Prolific User Username: larry_halpert Post Number: 96 Registered: 9-2003 |
Hi David, I only have gotten brand new sealed 14-16 ounce containers of R12 by the case. But now being further informed on these effects, I will prepare for an R134 changeover. Sorry about the seeming callousness. Larry | |||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1102 Registered: 4-2003 |
Larry, Don't feel too battered. In Australia we are particularly angry over ozone depletion and its carcinogenic results. R12 is a major Ozone enemy. The diligence of Australia in the banning of R12 for so long is recognised everywhere. So much so that even here in Switzerland the common label for sunscreen cream reads, and I quote from a purchase today: "Ultra-hoher Schutz LSF 50+ Die neuartige Formulierung enthält eine Kombination von UVA/UVB-Filtern und ist frei von Emulgatoren. Der hohe UVA Schutz, gemäss Australischem Standard und wertvolles Vitamin E schützen vor Sonnenbrand..." Basically, "this sun cream has a sunscreen factor of 50+ to Australian standards.". In short, there are but two strong Australian international standards: the price of wool in Australian dollars, and the Ultraviolet protection factors of sunscreens in accordance with the Cancer Council of Australia standards ! More to the point, John, I suggest that you do eliminate the leaks (preferably at source and not with sealants). Once the system is finally stable and leak free, convert permanently to R134a or its successors and expect no need for recharging in the foreseeable future. I am surprised at the deletion of the receiver sightglass as a new insert will do fine, as all our cars have R134a and retain their sightglasses. As David implies, a recharge is OK as a stopgap, but a full service including new oil, evacuation, and a measured charge of R134a is by far the best once the system is leak-free. RT. | |||
| John Aravanis Experienced User Username: krug300 Post Number: 25 Registered: 2-2005 |
Thanks for your valuable input. The receiver was purchased from Brabo, and I was told that they don't have sight glasses anymore. It was nice to be able to visually check the status of the charge. I will therefore locate the leak, introduce the agent/oil that blends with the existing mineral oil, attach the filling point adaptor and charge the system with 134. I think that with the Shadow's high BTU system the "lower" output of the 134 will not be noticeable. I just hope I have all this correctly in my head because the a/c shop here in Athens said to me that "we will do whetever you tell us....". Regarding the availability of R12, I am surprised to see that despite the strict laws forbidding its use, it is still available on ebay and other internet sources. | |||
| David Gore Moderator Username: david_gore Post Number: 662 Registered: 4-2003 |
Hi John, There will be a permanent small loss of efficiency resulting from the conversion to R134. To keep this loss of efficiency to a minimum, it is imperative that the R134 be weighed when charging the system so the compressor has enough gas to compress for complete liquefaction to be achieved when the compressed refrigerant passes through the condensor. If the gas charge is insufficient, the gas will only partially liquefy accounting for the bubbles in the sight glass and, more importantly, reducing the heat absorption when the liquid/gas mixture expands as it passes through the evaporator. I suspect the deletion of the sight glass on the receiver is a direct consequence of the change in recommended practice to charging the system by weight instead of measuring head pressures while feeding gas into the system. The practice of charging by weight will give certainty provided the vehicle's A/C system has been tested for R12/R134 conversion. | |||
| bob uk Unregistered guest Posted From: brig-cache-4.server.ntli.net |
forgot. The Shadow aircon is powerful so a slightly less than powerful refrigerant won't show. (Message approved by david_gore) | |||
| bo uk Unregistered guest Posted From: brig-cache-4.server.ntli.net |
In the UK R12 is forbidden by law. No Aircon in UK shop uses R12. Discharging refrigerant in to the atmosphere carries a heavy fine. And the enviroment police check shops equipment. My local aircon shop ( Lucus Service- prince of darknest ) quoted £110 to check the aircon vacuum and replace with R134a and additive oil. Which I think is a reasonable if not cheap price. (Message approved by david_gore) | |||
| whunter Prolific User Username: whunter Post Number: 180 Registered: 10-2003 |
Hello David Gore As per testing performed: Conversion from R12 to R134A has an average permanent efficiency loss of 14% to 38%. The wide variation is caused by fixed design/engineering factors of each individual system, and how well the conversion was performed. | |||
| Guy Boldon New User Username: guy_boldon Post Number: 3 Registered: 5-2006 |
SHADOW 17774- A/C I have lost power to the A/C unit. The clutch does not engage the compressor when applied. Is there a documented procedure which I may follow to trace the power line. I suspect that there is a break in the circuit but I need to know where to begin to look. Thanks. Guy Boldon | |||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1117 Registered: 4-2003 |
If you look at a theoretical wiring diagram for your car in the Technical Library on this site, you will see how very simple the circuit is. Best start inside the car and follow the chain. The same fuse feeds the clutch solenoid and the actuator flaps, so if the flaps work then it is unlikely to be a power distribution issue. After the fuse, there is a very simple contact in the main airconditioner selector switch assembly which engages the clutch whenever you turn the knob to call for any cooling. A simple test at the output of the switch with a meter or a test lamp will show if the switch is functioning when you turn it on with the ignition turned on. The output from the switch goes straight to the clutch through a blue cable with a purple stripe. If there are volts at one end and not at the other, suspect a broken cable. One caveat: many cars have now been modified in accordance with a Crewe bulletin to have a cycling clutch, which involves deleting the suction throttle valve and some minor wiring changes. As on the SSII cars, there may also be a fusible link at the compressor which will melt and inhibit the compressor if it runs low on refrigerant. Either of these may stop your clutch from engaging and are worth looking for. | |||
| Peter Colwell Experienced User Username: peter_colwell Post Number: 23 Registered: 3-2005 |
Guy, I had precisely this problem recently. It turned out that the gas pressure had dropped below a point where the internal safety switch closes. Once the unit was regassed, it worked perfectly. Peter | |||
| Glenn Amer Experienced User Username: recordo Post Number: 24 Registered: 4-2005 |
Gentlemen, A new compressor recently fitted made my car's air conditioning run so beautifully cold I was almost in tears. (And the car was quiet again, the old compressor must have been on the way out for a while). Unfortunately the suction relief valve is now leaking and my air conditioning man (kindly recommended by Tom at Bentley of Sydney) cannot attend to the car until next year - which upsets me as the Shadow is now my only car - I have forsaken my Daimler. The point here is that I am writing to ask if anyone has a copy of the bulletin to which Richard Treacy refers above - the one about deleting the suction relief valve and the wiring changes. (I looked in the technical section and couldn't locate it there). Best wishes to everyone for Christmas and the New Year, and thanks in advance, Glenn. | |||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1142 Registered: 4-2003 |
See the attached.
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| Glenn Amer Experienced User Username: recordo Post Number: 25 Registered: 4-2005 |
Thank you so much Richard! regards, Glenn. |
