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Discussion Starter #1 (Edited)
Just thought I'd throw this onto the forums because I havent found any rebuild guides for it and thought it might be useful to some to see the internals etc before undertaking i'm not saying this is the way to do it this is just how I went about it.

I am reinstalling A/C system into my car, I had removed it years ago because it was out of original R12.

I will be regassing myself with hydrocarbon refrigerant which has similar properties to R12 with about 1/10 of the cost. I will be performing thorough solvent flush of every line and individual part before reassembly with new nitrile seals. I am going to install a new expansion valve and reciever dryer.

The important part is to rebuild the compressor I think because these seals are often forgotten and end up pretty leaky.

I have a couple of Seiko units, these are a rotary vane compressor. The seals inside this unit were hard and quite damaged.




rotary vane compressors have a rotor which is turned by the belt system, with vanes that slide out and make contact against a sealing surface in the part called the cam ring, they suck the refrigerant/oil in, compress it and then eject it through reed valves on the outside of the cam ring. I will take more photos of this.



This is the interior surface of the cam ring, which as you can see has some scoring from reasonably large size contaminants, but the scoring isnt really as bad as it looks I dont think. The rotor and vanes are in good condition there is no scuffing to suggest seizure I think it is just the vanes have picked up contaminants which have become embedded and caused the wear over time... I will tidy this up with a fine hone stone just to take the highs off, and I will also just gently hone the contact faces of the vanes. really the way to get this back into nice spec would be to grind it on a cnc but thats just beyond the point in terms of $ - you may as well buy a brand new one, and if you were to do that you'd need to install new vanes.. to get a gas tight seal usually you need a surface finish of 0.1-0.3micrometer, so that would equate to an 400 grit hone, I will see if these scratches polish out with 800 grit whet stone but at the end of the day I have another AC compressor which is probably in much better condition internally, its in my storage shed which is 500km away and i'll grab it next time I'm back that way.

not suprisingly there are no spare parts really other than the seals for these compressors as far as I can tell.

This is the unit torn down, pretty straight forward.

There are several o rings that need to be replaced, now if you live in the US Virtualac.com sell the o ring kits and the spring loaded seal assembly as pictured very cheaply.

I have obtained the o rings from a local shop for about $10 am just going to re-o ring the spring loaded valve and housing because shipping is expensive. If this doesnt work effectively i'll buy the kits.



i'll take some more photos of the individual bits etc.

Essentially if this compressor doesnt work properly I'll only be out $40 aud for the refrigerant, and I might be able to capture it and reuse it . maybe!
 

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Discussion Starter #3 (Edited)


This photo shows the two o rings that need to be replaced here. Now to be honest I havent pulled this alloy plate off but I should to see if there are seals there that need to be replaced - I dont think there are, I think its permanently sealed from the factory. The two o rings are important, these are sealing the high side.



here is the side on view of the cartridge, the holes are where reed valves live, I have marked each side and removed to clean the surface with brake cleaner and re-loctite the bolts. the vanes compress the charge through the reed valves which are one way valves.



heres another view inside the cam ring, most of the thrust surfaces are really good, its just contamination in the bore, or low refrigerant induced overheating that has caused scoring.

[/IMG]

this is the cam ring top cover - not much wear




heres the end cover, there is one large o ring around the outside to seal it, but you can see the 45 degree inner flange is also another o ring sealing surface, inside the bore is the aluminium ring with an o ring in it as well. (its the second part of the carbon seal in the ebay picture)



this is the housing, you can see where the o ring has rotted into the aluminium I will clean that up. this o ring is the one on the cam ring in the above photo



rotor thrust surfaces are in good condition, vanes are too, thats just oil.





rotor and cam ring assembly...



this shows rotor shaft with carbon seal, inside that spring loaded seal is an o ring.
you can also see the o ring on the housing, this fits into the aluminium housing I posted above..






these are just pics of the clutch parts, the hub which retains the main AC bearing, the clutch plate and the magnet.

bearing is 40BD219

the clutch plate clearance should be around 0.5-0.7mm

the total system oil capacity is 170ml for seiki seiki 170 on c900
I will be using synthetic oil.

I will as I said be flushing each part with mineral spirits (because its hygroscopic)

I have a venturi vacuum pump to pull down the system to near absolute vacuum before charging.

there will be lots of electrical testing I think to get the system functioning correctly. at the moment both fans come on with coolant temp, but not sure if both will come on with a/c system activation, also the hydrocarbon refrigerant runs at lower pressure which may be below the low pressure switch operating range, so there are lots of variables!

at any rate there may not be further progress on this for a while because I want to check out the other seiko compressor I have at home to see if its in better condition!

plus no point doing anything too drastic until the replacement engine is in and running, then it'll just be a matter of bolting on the a/c comp and connceting all the hoses up!

ill add in the seal specs later but from memory they're around these sizes
nitrile
most of the seals are 2mm thick
the end case seal is 3-4mm thick

2x 20x2mm
1x 30x2mm
1x 30x3mm
2x 95x2mm

or the seal kits - from virtual air or autozone
MT2279 (o rings)
MT2078 (seal)
MT2029 (bearing)
 

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Discussion Starter #4 (Edited)



So got the system connected up, fully rebuilt compressor, had to squeeze the condensor back in with the 3" FMIC, which was a pain, had to make some custom brackets and also modify the front airdam, I have a spare for if I feel guilty down the track, I doubt I will haha




Vacuumed down the system for 30 mins, nil vacuum loss for 24 hours which is enough confirmation for me... the system has a new reciever dryer, expansion valve, all new o rings, before reassembly all the components were thoroughly flushed out with methylated spirits which is hygroscopic and blown out with compressed air until very clean. 180ml of SRO-500 synthetic non toxic refrigerant oil was added to the low side of the compresor. the one mistake I need to rectify is I didnt insulate the expansion valve bulb which I need to do.



R12 doesnt exist anymore in aus, and for 134 you need a licence to buy it and use it, so instead I decided on Hychill minus 30, a hydrocarbon refrigerant based on ultrapure isobutane/propane (yes flammable) but explosion risk is not that likely in reality due to its flash point, it evaps very quickly so has to be synchronised release and ignition source... the cool thing about hychill is that its 40 bucks a can for 450 grams, and you only need 300 grams (1/3 of weight) compared to standard refrigerants, so works out very cheap.

their process is to open high side with engine off, let as much refrigerant in, turn over compressor several times to make sure not hydrolocked, then close high side, start engine, engage ac and then let proscribed charge weight enter low side being sure not to let low side go over 80psi or so.

To get my a/c to work I had to bridge the coolant temperature cutout wire, and also bridge the wide open throttle cut out, if I am gonna flog the car I wont be running the a/c anyway lol. I also wired the a/c relay trigger 12v wire to pin 59 on trionic ecu to ^ the timing/rpm of the motor with a/c engaged to compensate for the load.

gotta say the rotary vane compressor does drag a bit on the engine !



think I overcharged it a bit, high side is meant to read about 150psi, but its ok



pretty darn cold, that was just at idle after 20 seconds, think its probably likely to get colder on the road with air flowing past the condensor!

overall couldnt be happier with the system and how its working. I'll keep my nose peeled for the smell of rotten cabbage (propane leak) or else kaboom :lol:
 

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Well done Ed,

Nice work on the rebuild , excellent write up .

a little concerned re your comments re flammability, having seen 2 systems blow off gas pressure in the last month , One via the safety valve , one via a crimp fitting, I hear what you say re flash point and synchronized ignition, the percentages are low , but they do exist ?

perhaps now that you have proven the Build and a 100 % sealed system you could consider having it re gassed with R134 ? there are many shops doing it for around $100 .

Does the Compressor have a safety valve on the 900 ? What is its settings ?
 

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Discussion Starter #6
I'm really only stirring. Two independent companies did risk assessments on hychill and found explosion risk to be negligible. It's very safe. 300g is nothing like 50kg of lpg in the boot of your car. And in te engine bay of an lpg car there is potential with crash for 30-100g of lpg to vent but lpg cars are legal.

This product has passed independent safety testing but you gotta be aware it's hdro and not do anything dumb with it.

Leaking petrol from fuel line is more likely to combust than a pressurised gas that vents to atmosphere. You need to have pretty good mixing of gas and air with high energy ignition source to create explosion (ie a heavy load relay arcing) before the gas flashes off.


What scenarios are you referring to. Car ac?

Car ac is a permanently closed system it will never discharge to atmo unless a seal fails. There are electronic switches to disengage the comprsssor if pressure too high or too low.

It's worth mentioning that hychill runs at much lower pressures than r134. And even a bit lower than r12. The peak pressure in my system despite rpm is around 175 psi. If a hose spontaneously burst it would likely vent majority of refrigerant but there are no active ignition sources except maybe alternator brushes which shouldn't really be sparking or cooling fan brushes.

In all th tests they did the passenger compartment was never compromised and because of its distinct rotten cabbage smell of ther was a leak id turn the car off and purposely vent the entire load to atmosphere and then find and fix the leak.

It cools way better than 134 is why I am going to stick with it.
 

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Discussion Starter #7
Plus 300g even if it was all accessible for combustion it creates a significant fireball not like a concussive blast that would shrapnel you to death.
 

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Discussion Starter #9
The new refrigerant is r1234yf which is flammable. This is widely used.

R439a the r12 replacement which doesn't require retrofit is flammable.

I think you'll find most split system air con and fridges now use flammable gases because they're cheap and effective.

There's no ban on hydrocarbon refrigerants in Asia pacific. And now there is no ban in the USA. EPA legalised hydrocarbons recently. Maybe the delay in the USA is because dupont and associated refrigerant manufacturers had a monopoly on the market and have pushed to keep legislation In place that allows them to profit from their specialist refrigerants.

GE Fridges use isobutane in the USA.

There's heaps of examples. It's very mainstream now. The only danger comes when peolle do stupid stuff with hydrocarbon refrigerants like two guys in a Pub basement in Australia cut through beer cooler lines with angle grinders that were filled with hydrocarbons. They died.
 

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Discussion Starter #10
There are inherent hazards. Systems using hydrocarbons need to be clearly labelled. But hey r12
And 134 have significant risks of poisonous gas or acid formation under certain conditions. Their volatility is similar to the flammability of hydrocarbons. You need a lot of things to go wrong to ignite gas. To get an idea of perfect compressed combustion just watch someone throw a propane can (for blowtorch or camp unit) in the fire on YouTube. The fireball and concussion wave is fairly big but it is compressed in a can. Any explosion that occurs in car setup will be from leaked gas. Not gas under pressure.

Not one incident has been reported of car with hydrocarbon exploding despite majority of cars in India and now China being gassed with hydro.

We're talking 300grams
 

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Few people have high-speed collisions with their fridge while the fridge's exhaust manifold is red-hot and there's a ruptured high-pressure fuel line.

It would not be my choice.
 

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Discussion Starter #12
yeah I mean thats fair enough that it wouldn't be a choice,

I've done a lot of research on it, and I've read the primary level research papers on risk stratification and testing... the australian government has looked into whether to regulate or ban the industry practice but it cannot find a good reason to.


Approximately 10% of all cars in australia 1.2 million are gassed with hydrocarbon, people crash all the time and there are no reports of explosions or fiery infernos despite 10% of all cars in accidents having hydrocarbon refrigerant.

http://www.environment.gov.au/protection/ozone/publications/cold-hard-facts-2
the quoted stat as detailed in the australian governement refrigerant industry report

hychill has been operating for 20 years, there are nil automotive incidents of note, the main ones are commercial where large volumes of gas have been used to cool industrial refrigeration units which have subsequently been dismantled or serviced incorrectly etc like the one I mentioned people cutting with an angle grinder in a basement, the gas leaked over the Lowest point of ignition concentration and there you have it.

anyway its one of those things, it cools like mad, I havent even fully tested it yet, I know it ****s on r134 because a mate had it and his air con in his c900 suckkkkeeeed so bad. this thing is icy and thats all I care about.

I got more chance of finding treasure than I do of being exploded in a crash from 300 grams of gas, I mean we threw propane canisters in fires at parties growing up and we're still alive... this is a different story all together
 

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Ed ,

Why I mentioned the safety valve on the compressor ... Does the 900 Compressor have one ?

I have had 2 instances of the AC venting to atmosphere in the last 6 weeks , yes I know its a sealed system with protection to prevent over pressurization , ( that protection can and does fail ) It is not just Failed O rings that can lead to Venting ...

The First instance was my original Viggen , IT blew off thru the safety valve on the compressor , which means that the Pressure switch on the condenser failed to shut power to the compressor when Over pressurizing .. the Safety valve was the second line of defence .. Why did it over pressurize , That i still do not know , but it was no longer a sealed system .

The second Instance was driving the new viggen home from Queensland freshly re gassed ... IT blew A hydraulic Crimp fitting on a hose , Root cause still unknown , but again you might say the protection failed... the pressure switch and the Safety valve IT vented with passion ! SO i can only assume at a PSI the Switch should have responded too ... The Safety valve is at an indelibly high pressure ( around 34 bar from memory )

I am not debating How safe it is or is not as refrigerant, I know you have done your own very thorough research on that, you Know far more on the subject than I ever will ... However .. The AC systems will and do leak and in fault conditions Its a high volume under High pressure leak . , don't consider for a second that it is a sealed system when doing your Risk analysis .. Because... THEY do not remain sealed ...obviously , Yeah 99% may be slow o ring leaks .. But as said Twice this Year for me ..Major BLOW offs .
 

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And having said all that .. ( we were typing at the same time )
The viggen that was re gassed with R134 , It read 7.5 Out of the vents ... when Cycling in .. So Not sure its the type of gas that was all to blame on your mates 900
The Viggen managed to maintain a 20c cab temp On 40 degree days fine .
 

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Discussion Starter #15
nah c900 comp doesnt have pressure valve, it will disconnct the clutch if too high or too low. but at 40 celsius the high side pressure is up to 400 psi, so things can go wrong at that pressure... even still if it does vent, the ignition temperature is over 400 celsius... potentially the lines where they run in proximity to the exhaust could cause a fire if there was catastrophic hose failure we'll see.. not fussed about it because 10% of cars have hydro and 10% of car crashes arent infernos

the viggens were designed for 134, so bigger better condensors and different seal designs in compressors etc...

the early c900s were r12, and so the retrofits often dont give the best results, but also probably problems with expansion valves and other things may be contributing to the poor results with r12 with early systmes.
 

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Your starting to throw more (pick a figure) percentages than Jim ;ol;

Remember that throwing the clutch on the compressor relies on a switch , My 2 examples illustrate clear Switch failure
IN the i st instance the safety valve let off at around 500 Psi , I think the switch was supposed to kick in at around 1/2 that.

As for throwing Propane cylinders into a camp fire.... Well i would have responded quicker to that , but typing when you are missing a few digits is cumbersome ...:roll: Time to give that one up ED !

Cheers mate and as said , nice work on the AC rebuild ..
 

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You folks make your own choices. I'm sticking with flame-suppressant refrigerants.
You all seem to be ignoring the red-hot manifold. For the sake of argument, let's call it an ignition source; a red-hot glow-plug.
In a front-end collision, it is likely that a fuel line will burst, and the fuel ignite. It is likely that the high-pressure flammable A/C gas would also ignite after the fuel splashes on the red-hot iron, and fan flames as it vents.
Again, you make your own choices, but have you seen burnt cars? All that's left is steel and the big castings; the 4 wheels have 2 cables on them (what remains of the tire beads).
It ain't pretty, and it happens real fast. Let's hope you're not dazed after the collision.

(Sorry for the rant, but I had mandatory firefighting training. Just about 8 hours' worth but enough to fight a couple of fires and get the **** scared out of me.)
 

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Discussion Starter #18
haha :cheesy:

yeah you make good points...

I can always change my mind provided things dont explode, I have tested the switches as part of the diagnostic process,

the point with hychill is that because of the way it works it doesnt generate as much pressure at temperature as standard r134, the high side pressures are much lower, reducing heat and strain on compressor and engine torque requirements, so theoretically it doenst reach as high pressures as r134 either
 

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Terrific write up. ;ol;

Jim, while the points you make may be valid, the pertinent point here is "R12 doesnt exist anymore in aus, and for 134 you need a licence to buy it and use it".

I had given up on DIY air conditioning work because you can't just go into a car parts shop and buy refill kits, as you apparently can overseas.

Anyway, once you've finished Ed, have you thought of imroving on those pathetic air ducts that push out air like an asthmatic blowing through a straw?
 

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Several years ago I read several studies about HC-based refrigerants in general, and my takeaway was that while they present a higher risk than non-HC-based refrigerants, the increase is so small it's almost not worth worrying about.

If you put on your conspiracy hats for a moment, there is an argument that says we have R134a and not HC-based refrigerant mandated because the Dupont is gigantic, and they could lock out competition with R134a and not HC-based refrigerants. The argument is that when (primarily) the US government started looking for refrigerants that were not ozone depleting Dupont fudged some numbers to make R134a appear more ozone friendly and less flammable than it actually is, some palms were greased, and R134a became the de facto mobile refrigerant. Years later, we all found out (SURPRISE!) the realities of R134a aren't nearly as benign as they were initially indicated. The solution, of course, is another complicated chemical that also locks out competition and also has some dubious test results. Mercedes has flat-out said "it's dangerous."

I don't and don't pretend to know, but I know these environment-corporation-government interactions are pretty complex, driven by money, and have suspect motives. :D

I use an HC-based refrigerant in my 1993 motorhome because an R134a conversion was *expensive*. My logic is that it's a 12,000lb plywood box carrying 100 gallons of gasoline in the back, 25 gallons of propane under the driver's seat, and couple pounds of R410a on the roof. A little hydrocarbon gas is the least of my concerns. It works *great*. ;)
 
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