Before I Hurt Myself... - Page 2 - PeachParts Mercedes-Benz Forum

loneranger · #16 09-01-2014, 10:02 AM

Quote:

Originally Posted by Adriel

Went to change the Schrader valve on the low side, started removing, and got hissing. Gauge shows 0 and the A/C compressor isn't coming on. Figure I better check so I don't hurt myself.

Is it alright to just slowly vent the remaining pressure?

How much of an environmental impact is there releasing a small amount like this into atmosphere?

Thank y'all in advance!

Ah, nuts, cows farting releases 10,000 times more junk into the atmosphere. There's probably 1-2 psi in the system. It won't hurt. Watch your fingers though refrigerant will freeze your fingers. Hot air from brainwashed bureaurat automatons releases more harmful pollutants in the air than your tiny amount of refrigerant. Our wonderful government has been dousing us with Chemtrails for years to make us sick and passive so we will not resist them. Go to Freeman tv if you want to know how bad things are.

97 SL320 · #17 09-01-2014, 10:11 AM

A high post count means nothing.

For an old style R12 fittings, a metal cap will fix the leak problem. For R132 type fittings, a good plastic one with an o ring will work also.

Some hoses will wick moisture ( mostly the old style R12, Barrier hoses are used for R132 and should be less susceptible. ) It sounds counter intuitive but even with internal pressure moisture will transfer.

A similar situation occurs with in floor hot water heating where oxygen will enter the system through the plastic pipe. This even occurs on high purity nitrogen systems if the proper piping isn't used. ( laser beam path purging )

The dryer does not need to be change every time the system is opened, it does not absorb moisture fast enough to warrant a change. It makes no sense to change an hours / days / weeks old dryer if other work needs performed ( Baring a compressor failure that makes metal )

It does need to be changed as a precaution if major work is being performed as you won't know if the descant is saturated. ( Commercial systems have a moisture eye to monitor system dryness. )

leathermang · #18 09-01-2014, 10:18 AM

Quote:

Originally Posted by 97 SL320

A high post count means nothing.

The dryer does not need to be change every time the system is opened, it does not absorb moisture fast enough to warrant a change. It makes no sense to change an hours / days / weeks old dryer if other work needs performed ( Baring a compressor failure that makes metal )

It does need to be changed as a precaution if major work is being performed as you won't know if the descant is saturated. ( Commercial systems have a moisture eye to monitor system dryness. )

You are just wrong.
I have the Mercedes FSM on Air Conditioning.. and it says change it..

People with REALLY LOW post counts ... meaning they did not participate in the AC wars of Old...... saying ' some unidentified person told me'... and saying things WHICH ARE CONTRARY TO ACCEPTED INDUSTRY STANDARDS.....are suspect...

mannys9130 · #19 09-01-2014, 11:23 AM

Suspect me all you want. I'm not offended.

I'm sticking to my guns. Industry standards are one thing, DIY is a whole different animal.

leathermang · #20 09-01-2014, 11:29 AM

Manny,
You do not seem to have much confidence in Adriel's ability or interest in learning how to do it correctly......
Where does that come from ?
I think he did not know the reasons for changing over the fittings.... thus did not...
but I think now that he knows there are good reasons... he will address it...and try to start out with a system as dry as he can figure out how to get it... before putting in costly refrigerant ....and those R22 and dry nitrogen pressure tests do a dual service.... as a further drying process...... two for the money....

it has not been mentioned lately ... THE REASON..... we shoot for really really dry AC systems.... is that the AC oil mixes with the moisture....and makes ACID.... which can corrode some of the metal parts in the system from the inside... typically causing FLAKES to come off... and be pushed around the system until they reach a tight spot.... like the TXvalve .....and clog it up.. or on other systems.... the orifice valve..... so for longevity... a really dry system is important...

leathermang · #21 09-01-2014, 11:35 AM

Quote:

Originally Posted by mannys9130

.....
I'm sticking to my guns. Industry standards are one thing, DIY is a whole different animal.

Industry standards are based on the PHYSICS of the situation...
DIY has the potential for doing a better job than someone with time constraints at a repair shop.

mannys9130 · #22 09-01-2014, 11:38 AM

I may have a lost post count, but I've lurked hard for quite a while and still do. You get to know the basic motivation level of different people when you've read the threads started by them. I just think the procedures used by industry professionals are almost unobtainable by the average DIY shadetree. I don't lnow anybody that has dry N2 or R22. Like I said, at what point does it stop being worth the extra steps and hassle? A dryer replacement, oil top off, 45 minute vacuum, and R134a recharge will be just fine for nearly every DIY mechanic. If there are slight leaks, you may need a recharge in 2 years. Big deal, it's 10 bucks a can. EPA law allows for topping a leaking system, even with R12.

leathermang · #23 09-01-2014, 11:48 AM

Quote:

Originally Posted by mannys9130

I may have a lost post count, but I've lurked hard for quite a while and still do. You get to know the basic motivation level of different people when you've read the threads started by them. I just think the procedures used by industry professionals are almost unobtainable by the average DIY shadetree. I don't lnow anybody that has dry N2 or R22. Like I said, at what point does it stop being worth the extra steps and hassle? A dryer replacement, oil top off, 45 minute vacuum, and R134a recharge will be just fine for nearly every DIY mechanic. If there are slight leaks, you may need a recharge in 2 years. Big deal, it's 10 bucks a can. EPA law allows for topping a leaking system, even with R12.

Ok.. now you know someone with N2 and R22... the N2 in a cylinder from my local welding supply...and a 15 oz can of R22 from Ebay.

Here is the problem with your conception of a ' leak' ... that since the system is under pressure all the time.... that leaks are OUTWARD ONLY...
but that is not the case if you examine the system by section.. you can have a leak pulling in air and moisture...
So in two years you can have that moisture mixing with the refrigerant oil... making ACID....and corroding the system so that you have to take it apart and flush it... maybe replace the TXvalve.... etc...

vstech · #24 09-01-2014, 12:59 PM

Now now fellas. Contradicting each other isn't doing anyone any good.

If the op askes what to do in a situation, and members argue about it, then the op gets confused.

First off, r134 is not ozone depleting, it's a carbon massive greenhouse gas...
Second, venting it is not allowed for a trained professional, but no license is required in the us to purchase or dispense it, so do what you like.
If you open the system just for a valve core that is not under a vacuum, I'd not change the dryer. If the system was flat, for an unknown time, I'd pressure check, leak fix dryer change and evacuate to 1000 microns to be certain no moisture is present, and recharge.
45 minutes may or may not be enough time on the pump. 2 hours may or may not be too much... Micron gauge tells the story.

vstech · #25 09-01-2014, 01:03 PM

Oh, N2 is not critical... Any dry pressure gas is fine... Except O2 of course!!! CO2, N2, argon, helium, etc... The last refrigeration sled I installed was charged with Helium! Amazed me, but since it's the smallest non combustible gas, a leak free system is assured!

Lowes has a CO2 kit for nail guns that's handy for pressure testing... $50

funola · #26 09-01-2014, 01:26 PM

Quote:

Originally Posted by mannys9130

I was told that for non-hermetic A/C systems a 45 minute vacuum cycle was ideal. If you draw a vacuum for too long, atmosphere and more water can be drawn in through small leaks or by pores in the hoses. Hours is too long for a car A/C system.
....................

I'd think this may be very true for the W123 with the R4 compressor which has a spec. leak rate through the compressor's stepped ports (o-rings). If it can leak out refrigerant, it can draw in moisture during vacuum evacuation. The longer it is under vacuum, the more moisture can be drawn it.

Adriel · #27 09-01-2014, 02:32 PM

Thank y'all for all the replies!

So many I am overwhelmed!

I don't give a rats behind about how many posts someone made so long as accurate and/or gets me going in the right direction. We all have to start somewhere!

The more folks are knowledgeable the quicker someone can get help as the experts aren't available all the time!

I think I need to clarify. Tram's wife owned this Mercedes and is a trained mechanic for V.W. and Mercedes. When she owned it, he converted it to R134a, I believe before I bought it. He put an adapter on the low side and gave me a gauge, telling me never to touch the high side.

Yes it might be illegal to have R12 fittings, but R134a fittings are not available for most vehicles that had R12. It is unreasonable for a law to demand something that is an impossibility!

Further, I would never take it to another A/C shop, as total waste of money and only made things worse! I am again and again reminded why I have to do my own work and/or get help from friends! So there will never be an issue of someone mistaking the refrigerant.

If I need to get a new drier, fine. They are not that expensive and I don't mind the wait. I have learned that getting in a rush and/or doing things half right only leads to more loss of time and/or money.

Quote:

Originally Posted by vstech

Now now fellas. Contradicting each other isn't doing anyone any good.

If the op askes what to do in a situation, and members argue about it, then the op gets confused.

First off, r134 is not ozone depleting, it's a carbon massive greenhouse gas...
Second, venting it is not allowed for a trained professional, but no license is required in the us to purchase or dispense it, so do what you like.
If you open the system just for a valve core that is not under a vacuum, I'd not change the dryer. If the system was flat, for an unknown time, I'd pressure check, leak fix dryer change and evacuate to 1000 microns to be certain no moisture is present, and recharge.
45 minutes may or may not be enough time on the pump. 2 hours may or may not be too much... Micron gauge tells the story.

Thank you John for helping be the captain!

You are a very good moderator!

I know R134a is bad for the environment, thus why I was seriously thinking of going R12a, but now have some doubts. However, I don't know at what point it is bad to have R134a go into the atmosphere.

If it isn't legal with someone with a license, then I am not going to do it! License means professional, and I want to be at least that!

I have to replace the condenser... So when I order a new radiator will just order a new drier.