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Air con recharge MKIII by Torchd on 21 Jul, 2009 10:00
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Hey guys... Would any one know how much R134 refridgerant does the mkIII air con system take??
Please tell me in grams..
Thanks! -
#1 by Torchd on 22 Jul, 2009 23:25
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Bump...
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#2 by jtanguay on 23 Jul, 2009 09:36
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don't use r134a. use HC-12a or similar brand (hydrocarbon refrigerant)
i recommend getting duracool as their cans come with the oil already in it so be sure to shake the can up real good. if its been sitting for a real long time you might need to run the duracool duradry or pull full vacuum for a few hours, or replace the receiver drier. then use duracool a/c oil chill can and make sure you shake the poop out of that can to get the oil to come out right.
for a passat mk3 i found a site that recommended approx 2 cans of the duracool (i did the math, but dont remember the hard numbers) but what you really need to do is just use a thermometer in the vents (i think the achievement is 40F) and buy the duracool charging hose and 2 cans with the other duradry if you need it and a/c oil chill if its been sitting dry for a while. they also sell duracool system seal that can actually seal pinhole leaks in the system, but most of the time its actually the schrader valves that leak, so when someone hooks up their machine to your car, it seems like theres no leaks, but when they take their hoses off, it slowly leaks out there. this can happen especially if the system has been overheated, due to the rad fan quitting. one thing i never understood is why they don't have a refrigerant high temp shut off switch... they have a high coolant temp a/c shut off though. the high temp refrigerant temp shut off would save people a lot of headaches and having to recharge their systems...
so back to the charging procedure. the instructions say to hook up the charging hose to the low pressure side (you can't mix the two up as there is a size difference) first off, find the pressure switch harness and get something to bridge the wires (you might need to do this, or you might not. leave it connected for now but be ready to bridge it in case) now start the car and put a/c on full. with the charging hose hooked up to the low side, and the can hooked up to the charging hose, puncture the can with the twist valve, and then invert the can and slowly unscrew the valve and watch the gauge carefully. when the pressure reaches the blue, screw the tap in to stop the flow, you might need to wait a little bit for the pressure to equalize in the system so the pressure switch kicks the a/c clutch on. charging my system i didn't want to wait so i just bridged the connection myself and the compressor sucked the refrigerant through the system. all i did was charge my system up till the gauge was at blue and the compressor was on. when the compressor is off the gauge will read quite a bit higher though, so don't get tricked by this. i think the compressor cycling once every 2-3 minutes is okay.
the first can is crucial as you might find that you have a leak somewhere. don't start with the second can if you hear hissing or start losing pressure or cooling. you also need to make sure that the rad fan turns on with the a/c. if it doesn't, then you need to take care of that first. i had to change an o-ring on my system because it was totally destroyed by the heat... you might need to do the same.
now on to the benefits of duracool or other hydrocarbon refrigerants. r134a is a blend of gases with one of them having a very small molecule. this molecule can leak out of a system which would normally hold r12 or HC-12a just fine, and leave the rest of the gases in the system, making it seem like there isn't a leak but a greater problem. HC-12a has a bigger molecule than even r12, so the likelyhood of leaks is greatly reduced. with r134a a recharge isn't just taking a can and topping it up. the whole system must be evacuated, and fresh refrigerant installed. this is because of the small molecule that likes to escape. with HC-12a, you can simply top up at anytime if you have a minor leak. there's also lower compressor head temperatures, so your whole a/c system should last longer, with lower pressure needed than r134a. but just remember that its most likely the charging valves if you have a leak
hope this helps you
i just fixed my sisters a/c for her bday and she was very grateful. her pt cruiser rad fan low speed quit on her, so i installed a resistor going from the low speed to high speed, and it works great now with the duracool 
i can even describe the events that took place for her a/c system to stop functioning. a hot day blew the internal resistor in the fan, so the high speed worked (so the engine wouldn't overheat, but come pretty darn close) but the refrigerant did overheat and started leaking out anywhere it could. the pressure switch cut off the a/c when it got too low, and whamo no a/c. this is why a high temp a/c cut off switch would be such a great idea. 
either that or an indicator light for the rad fan being broken, but i like the auto shut off just in case someone doesn't pay attention
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#3 by Torchd on 24 Jul, 2009 01:03
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Thanks man for taking the time to write such a detailed and proper reply. Really appreciate it!
You have said that I shudn't use R134? Why is that? my cars system is designed for that type of gas not R12. Wouldn't the compressor go bad if i use R12?
And When you talk about cans, how much gas is in their in a can? the cans I can get here are 250 grams each... so how many will I need to re recharge an MKIII golf right hand drive ac system?
The brands which you have mentioned are not available here so it would be really helpful if you give me the specs of all the things so that I can look for same spec stuff available here.
Cheers!
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#4 by jtanguay on 24 Jul, 2009 08:17
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Thanks man for taking the time to write such a detailed and proper reply. Really appreciate it!
You have said that I shudn't use R134? Why is that? my cars system is designed for that type of gas not R12. Wouldn't the compressor go bad if i use R12?
And When you talk about cans, how much gas is in their in a can? the cans I can get here are 250 grams each... so how many will I need to re recharge an MKIII golf right hand drive ac system?
The brands which you have mentioned are not available here so it would be really helpful if you give me the specs of all the things so that I can look for same spec stuff available here.
Cheers!
ah if you can't get the hydrocarbon refrigerant then you might have to stick with r134a
that stuff can actually cause tumors on your testicles if you're exposed to it for long enough periods although just charging your system once shouldn't be so bad. if you can still get R12, that stuff will work though.
read more at http://www.duracool.com/Duracool/purchase.html check out their FAQ for more info on the benefits of their refrigerant and the toxicity of r134a. it also tells you how much duracool you need vs r134a or R12. the lower compressor head pressures mean that your compressor will last longer too i don't really follow how much the system needs, i just fill it up using their gauge and watch the vent temperature, and how often the a/c clutch is being engaged.
you might even want to check out on becoming a distributor for their products... i'm sure there are lots of people in Pakistan who need A/C and are tired of r134a and all its complications... could be a wicked business opportunity for you looks like the nearest supplier is in Indonesia!
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#5 by jtanguay on 25 Jul, 2009 07:09
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also don't forget to check out my post in the FAQ on how to do a heater core bypass. the problem with the mk2/mk3 airboxes (old ones) is that the foam can actually crumble and give a bad seal... so the natural convection from the heater core can actually mix with the cold a/c air warming it up, making it seem like your a/c system isn't working as it should.
http://www.vwdiesel.net/forum/index.php?topic=20448.0 -
#6 by Torchd on 28 Jul, 2009 07:12
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Thanks man but I dont think any one here would be interested in asuch a product since people here are thick! They dont care as long as the aircon blows cold air!
These a sticker under my MK3's hood. Its green and instructs on recharging of the air con system. Says 800 + 50 grms. Does that mean I am suppose to put in 850 grams of refridgerant?
Cheers! -
#7 by arb on 28 Jul, 2009 07:35
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Thanks man but I dont think any one here would be interested in asuch a product since people here are thick! They dont care as long as the aircon blows cold air!
These a sticker under my MK3's hood. Its green and instructs on recharging of the air con system. Says 800 + 50 grms. Does that mean I am suppose to put in 850 grams of refridgerant?
Cheers!
I would think so... and it sounds about right. Could be 800g - 850g. What size cans do you get there? Here they are usually 473g each. -
#8 by jtanguay on 28 Jul, 2009 11:49
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Thanks man but I dont think any one here would be interested in asuch a product since people here are thick! They dont care as long as the aircon blows cold air!
These a sticker under my MK3's hood. Its green and instructs on recharging of the air con system. Says 800 + 50 grms. Does that mean I am suppose to put in 850 grams of refridgerant?
Cheers!
here in Canada we're not allowed to purchase r134a without a licence, but i can understand in other countries where its available on the shelf to anyone... but the price of the hydrocarbon refrigerant is roughly the same, and is a superior product... too bad most people aren't smart though 
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#9 by Zulfiqar on 29 Jul, 2009 11:54
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I would suggest charging your unit with manifold gauges connected and keep checking your liquid and suction line pressures at fast idle speed, Ive never seen a car that would take exact amounts of refrigerants as mentioned on the sticker..
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#10 by theman53 on 29 Jul, 2009 19:35
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I really want A/C in my car...can we use any parts from newer golfs, jettas, passats, bugs??? The reason I am asking is when taking out the radiator and core support and A/C condenser the line broke off of the passenger side. I figured I would have roughly 800 more dollars into this car if I did all of the A/C stuff and made it new. If I could use slightly used stuff from a newer wreck I think I could do it just as reliably and cheaper as junk yards are full of good stuff.
The system hasn't worked in years and I would rather replace everything now while it is entirely apart then do it later when I have money. -
#11 by theman53 on 01 Aug, 2009 05:25
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anyone know?