91 M5. I want to evap all the freon and disconnect a hose near the compressor and clean out the screen. Then refill with correct amount and test both high and low pressures.
What all do I need to do this correctly?
Call a local mobile AC service
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Vacuum pump, gauge set, refrigerant scale, leak detector and an education on how to properly charge the system. Probably a new drier too.
Unless you plan on doing this a lot you'll be better served by seeing a pro and paying the fee.
If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue
You need ac in Alaska?
demet
subscribed, this seems like a very interesting thread
I would say at this point system need to be completely taken apart and even if all working all 0-rings and dryer need to be replaced.
Good time to convert to R134a
Pump + gauges can be bought cheap from HF. Scales is not absolutely necessary, can be filled "approximately" For example, 1550 grams +-50gr needed. 12Oz can = 340gr. So, car needs 4.84cans. Just fill with 5 cans and you will be OK
This all (taking apart, flushing, reassembly) will probably cost $1k+ in labor. If OP feels like he can do it - I'd say go for it.
I would never start with this invasive of a procedure. That's like finding one weak bushing and without checking the rest, ordering an entire suspension refresh kit.
Is it likely you will find other weaknesses? Yes. Might you be throwing away lots of money to replace perfectly serviceable components? Also yes.
Pressure check the thing, first, and see what you're working with.
I agree a conversion to R134a is a good idea, unless you have that rare resource of a reliable and affordable R12 supplier.
Those o-rings 25 years old. Cost pennies and system already open. Me personally - I did exactly that - replaced all suspension components at once in my car. I didn't feel like my time worth going there multiple times and wanted to start from scratch.
Every case is different though. If history of AC was known - it would be different. But now - I would make sure everything clean and tight. Couple hours of work worth it.
The AC has been converted to R134A and recharged but would only blow sort of "cool" for about 5 minutes. My low pressure was way too high and the tech from Bavarian Professionals suggested a screen in one of the hoses may be clogged up. So I'd like to get it cleaned out and recharge, then see what happens.
"System is already open" is a very different thing than "every hose and fitting is already removed". We're talking a ton of easily-stripped, tough-to-access components, here.
I agree 100% that anytime you have reason to remove or disconnect an AC component, you should replace the O-rings. Good practice.
I've had cars that needed every major A/C component replaced despite having a "known history"; and then others that never worked under my ownership, and one replaced component (with new O-rings at that component only) was all that it needed to hold pressure and blow cold for years.
A good shop, or guide, a pressure and leak test will tell you exactly what you may need to replace.
Not saying it's not true but I haven't seen screens in hoses before... Dryer is the only "filter" in a system AFAIK. But maybe E34 is different.. I did repair handful of AC systems but not AC technicial by any means.
Low pressure is high.. What does it mean? How is high pressure? Maybe compressor is out?
If screen clogged, then I would ask WHAT clogged it? There should be nothing in a system that can clog any screens. And if there is - it would be shavings/etc from burnt compressor.
- - - Updated - - -
What you say is all logical and makes total sense when you pay shop to repair it. But my labor is free to a degree and I work on this car for fun. To me it makes sense to make sure everything flushed, checked and recharged. My AC leaking somewhere, wasn't able to pinpoint with sniffer I have, so I just put some refrigerant to go through the summer. In a winter I will do exactly that. Flush/clean everything and replace every o-ring. From what I see - every hose/connection acessible from under the hood, should be no big deal. Plus, AC clutch seem to make noise, will replace bearing as well. Evaporator is my fear. If I have to go there - orifice tube will be replaced just because.
Last edited by katit2; 08-10-2018 at 05:17 PM.
Correctly? A $4000 AC charge machine that can recover refrigerant, separate oil from it, weigh them, apply a vacuum, and recharge the refrigerant with the correct amount of oil. Autozone/Harbor Fright tools can do a vacuum and a charge, but not recovery. It takes a little training to use one of the $4k devices, and to do it legally you also need EPA certification. It helps to have a leak sniffer too.
I used to work in a shop and was trained to use such a machine. Since then I've tried to do my own AC and learned that proper recovery is impossible without one, and you can't rent one anywhere I've seen.
EXACTLY why I said what I said. You can do pretty good job yourself. BUT. You need to take some stuff apart and flush whole system. Not as hard as it sounds.
Then put required amount of oil in components and you good.
Those machines do not remove all oil from a system, should remember that! Any system that is not factory sealed - I don't trust. People use crazy "self sealing" cans, add oil with dye, etc. You can never count on system containing correct amount to begin with.
Oh yeah, stay the hell away from stop-leak type products, in general, but especially in an AC system. Dye, however, is standard practice, safe (if correct dye), and a very good idea.
Last edited by moroza; 08-10-2018 at 08:28 PM.
I found this AC machine locally on Craigslist
https://anchorage.craigslist.org/tls...622264294.html
Assuming it functions, would that be everything I need to do it correctly?
I am wondering if those machines were available in 1991
That one looks like it's from 1991. And yes, it'll do what OP needs it to, but it better come with instructions.
On the all my cars I do the following.
Take the system apart and flush everything including condenser and evaporator.
Replace the expansion valve.
Replace the drier. $30 https://www.rmeuropean.com/Products/...69-MFG326.aspx
Sanden 508 compressor $120 from ebay.
Custom Sanden compressor brackets $40. I have a couple of sets left.
Build 2 hoses. You can get them done for $35 each at coldhose.com or you can make your own.
Add 5 oz ester oil to system. $10
Fill with 3 cans of r152a. $4 each. r152a has similar performance to r12 and is so environmentally friendly you can vent it to atmo. Google it.
Tools:
gauge set, I use this one https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Vacuum pump, I use this one https://www.amazon.com/Yellow-Jacket...70_&dpSrc=srch
but this one works fine also https://www.amazon.com/Robinair-1550...70_&dpSrc=srch
ac hose crimper, I use his one https://www.amazon.com/MASTERCOOL-71550-Black-Manual-Crimper/dp/B000WBQ4U2/ref=sr_1_1?s=automotive&ie=UTF8&qid=1533992766&sr= 1-1&keywords=ac+hose+crimper&dpID=51YU0d77rML&preST= _SY300_QL70_&dpSrc=srch
All this for a fraction of the cost oem.
cheers.
demet
I was replying to colt601 and his M5 which has a similar setup to the my m30 in my 89 535. The m30 has these types of older style fittings,
The fittings are readily available from many places. Your 94 has the newer style fittings. Not sure where you would get them, but usually if you need a new hose then you can use the existing fittings from your old hose and make a new hose out of them.
Last edited by demetk; 08-13-2018 at 11:08 AM.
demet
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