Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 05-22-2009, 11:46 AM
mobetta's Avatar
(Oo{-I-}oO)
 
Join Date: Mar 2006
Location: minnesota,hey.
Posts: 1,841
My AC thread

so I am getting ready to tackle one of the last things that doesn't work on my car. ( the Cruise that failed last week was(hopefully) just the linkage came loose)I really dont NEED Ac in MN, but we already hit 97 in the metro, and the wife is 4 1/2 months along, so I think she will enjoy it.

the history is this.
I had no AC when i got the car- surprise, surprise. I had the r-12 evac'd at a shop, then I added-(shhh...) the freeze12 crap that seemed so wonderful at the time, including an oil charge. had decent cooling for a few weeks, and the compressor started rattling. so I unhook'd it before any black death(I hope) could occur.

at this point, 3 yrs later, I have 0 psi readings at the low port. I also have a rather redneck hose patch on one line-I have a good replacement for this, but I reckon that is where all my f12 went.

does this mean that my F12 is gone, and I can open the system- to replace the compressor w. a rebuilt I have, and replace the one line, exp valve, R-D unit, all orings, etc-without"venting"(it seems the system already "vented")

I plan on flushing the system, replacing said components, and charging it w/ r-12 at Graplr's, as he has a charge machine, etc.......
I will prolly use a universal oil, so that if I ever did convert, the oil would not be an issue. good idea- or no??

should I replace the low pressure switch on the RD?

so what do I need to add to my shopping list??

I have the compressor and the upper line. the compressor was on a car I bought w/ a bad engine, but good AC- (r-12 AFAIK.) is there a flush procedure I should follow to eliminate any possible oil cross contamination??

I need-

receiver/drier

exp valve

O rings and seals- I see a whole car kit- worth it, or can I just buy the pkgs I see @ my FLAPS?? will this have the compressor seals and the RD seals?

oil- how much/ what type

flush in a can- 2


Thanks for the advice.

Reply With Quote
  #2  
Old 05-22-2009, 12:04 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
Well, I am glad you explained your circumstances....clearly you understand that without those we have a hard time getting much sympathy for lack of AC in Minnesota ... LOL

I really do not know of any ' flush in a can' which I would use... the flushing procedure is pretty specific if done correctly... which pretty much means flushing until clean flush comes out...

Oil... Castrol Refrigeration oil... premium mineral lubricant for R12 AC systems... cold flow 500 is what I would use... keep it closed just like the rec/dryer until about to be used.

Nylog in the proper color for your orings is important when putting it together...

There are great threads in the archives about these things...

Compressor ' flushing' by hand with new oil is discussed in archives.... do not hydraulic lock it..... that would ruin your whole day...

Tell us about your flush procedure plans for the rest of the car...maybe we can keep you on the 'straight and narrow' path ....
Reply With Quote
  #3  
Old 05-22-2009, 01:13 PM
dannym's Avatar
I'm not here
 
Join Date: Oct 2004
Location: Deltona, Florida
Posts: 2,360
I've heard positive things about the flush in a can stuff.

Not much else to use if you don't have access to an air compressor.

Grapir will keep him straight.

Danny
__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination
Reply With Quote
  #4  
Old 05-22-2009, 01:26 PM
racebannon's Avatar
parts or payments
 
Join Date: Mar 2009
Location: Moretown, Vermont
Posts: 33
not really AC advice, but...

My wife is 4.5 months along as well, due 10-06. my AC does not work either, not needed much here in VT, but this means that there will not likely be any long road trips in the benz this summer...

Good luck with the AC - I'll be watching the thread.
__________________
Blue '83 300D "Domobile"
Red '73 Cimatti City Bike (moped = fun)
Reply With Quote
  #5  
Old 05-22-2009, 01:42 PM
mobetta's Avatar
(Oo{-I-}oO)
 
Join Date: Mar 2006
Location: minnesota,hey.
Posts: 1,841
Well, I have air and many tools which use it. So what is the best way to flush with an air compressor?

I was thinking of opening everything that is easy to get at and using the can o flush. Is there a better method?
__________________
1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.
Reply With Quote
  #6  
Old 05-22-2009, 04:55 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
The MB AC manual suggests you take the old Txvalve and turn it into a flushing fitting..you won't be using it again anyway... you pretty much take the hoses apart and flush from the firewall forward.... there is a flushing ' gun' for using liquid flush agent...probably much cheaper than the cans....
There is lots of stuff in the archives about this... I am in the middle of a stuck axle nut on my Gravely 5665...
Reply With Quote
  #7  
Old 05-22-2009, 05:59 PM
mobetta's Avatar
(Oo{-I-}oO)
 
Join Date: Mar 2006
Location: minnesota,hey.
Posts: 1,841
Thanks for the help- and good luck with the job at hand.

I reckon I can rent the flush unit from AZ or oreally and use the liquid flush- it is WAY cheeeper, and I do have air. so get the EXP valve apart, and push everything out from there. I will hev the Compressor out, and the low sde hose- up over the front of the engine- is being replaced. should I unhook and purge it elsewhere?

Agian- I removed the compressor from service as soon as it started knocking, not after it froze up, so I dont think I have suffered black death, but I guess I will know more when I flush it. mostly I ned to get the old oils, etc out, so I can start anew.

I will know a bit more next weekend when I verify the compressor I have is set up for r12.



I have been reading up on the topic- there is a pile of stuff to wade thru, alot of BS, too- so I'll keep trudging.

What would be the "right color" Oring- green or blue? My FLAPS carries lots of green ones.

At this point, I really just need to know if I should order anything other than the exp valve and the drier, so it can be here by next weekend, too.

We are planning a trip to the badlands(or Batmans- as the 2 yr old says) second week of june, and if I get some AC, the wife might not make me rent a Prius...)
__________________
1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.
Reply With Quote
  #8  
Old 05-22-2009, 06:50 PM
Registered User
 
Join Date: Aug 2007
Posts: 35
You are on the right track. I am also going through a similar situation with the A/C in my car.

O-rings- the green HNBR o-rings are what you are looking for. probably best to get them locally. Make sure to use nylog sealant/lube on the o-rings when installing them.

You might want to consider adding a bit of UV dye when charging the system... this will help find leaks in the future.

Make sure that before the system is charged it gets a nice deep vacuum pulled on it for at least an hour. This will remove moisture from the system. It is very important that a vacuum is pulled!!

I believe 8oz is the proper amount of oil for systems with the R4 compressor (recommended by AC DELCO)

You may have a hard time finding a flush gun to rent. Both of my local autozone and oreillys do not have them for rent.
Reply With Quote
  #9  
Old 05-22-2009, 07:25 PM
Registered User
 
Join Date: Oct 2005
Posts: 4,263
No reason to not use green rings.

What wasn't mentioned about the flushing yet is the purging. It is imperative to remove all traces of flush agent from the system, or it will contaminate the oil. A lot of dry air is required.
Reply With Quote
  #10  
Old 05-22-2009, 08:29 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
From what I have read...and I have read a LOT.... I do not suggest putting in any leak dye... you will see when you take apart the Txvalve how small the spaces are there... and how critical that item is...
For being sure after your flush...and having put the CORRECT color Nylog onto those orings as you install them.... at first a pressure check with nitrogen and 4 oz of R22 is allowed to be used for leak finding...and let out into the air afterwards... legally...
So that means an electronic leak detector to check it in the pressure mode...which is what it will be in while working...
many only use the vacuum keeping test...but that checks the orings pulled inwards instead of how they will be expected to stay tight in working mode... when evacuating I would not do it less than overnight... what is the rush ... you do not want to be messing with this stuff for the next 5-8 years do you ?
If you rent a vacuum I would suggest one that can pull 50 microns...

I guess I am old and conservative about some things... but I would not take a family on the road without several LONG ' shake down' cruises.... get the prius and enjoy yourself...
Reply With Quote
  #11  
Old 05-25-2009, 02:04 PM
mobetta's Avatar
(Oo{-I-}oO)
 
Join Date: Mar 2006
Location: minnesota,hey.
Posts: 1,841
What about the low(or high low) switch- do I need to replace, and which one should I use??
and I reckon I use GREEN sealant with Green orings...?

I will be doing the shop at a fellow members house w/ a recovery machine and a charge machine, so if we get a leak right off, we can just evac and recover. I dont have Nitrogen on hand, so what are the alternatives?

I will be pulling vac for a long while, but maybe not overnite.

the oreally doesnt have a flush gun for sale or rent, but they have liquid flush-$10.99/L or can o flush for $18. I haven't been to Napa or AZ yet. could I use the EX valve w/ some fittings hooked up to a garden sprayer- push liquid flush in, soak it, then hook up comp. Air to dry/ purge?


I am not too fond of prius's ,and still a lil' bit young and dumb... so I will be driving the Benz'-just a matter of with AC or no AC. it is only early June, not August. we have tint and a cooler. the 93 volvo's condenser fittings corroded right off, so I am NOT doing the AC in that. She can always ride in another Prius( we are caravanning out w/ a friend who is renting a prius- therefor that great Idea from my wife.)

if it were August with a 3 yr old and a 7+ month along wife- I think I'd go to the local waterpark instead of SD. Thinking back, when I first did the freeze 12 was when we were expecting the 3 YO. That did work- for a few of the hottest weeks. this time around I even replaced the accumulators for her.LOL...no more bouncy ride= happy wife.
__________________
1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.
Reply With Quote
  #12  
Old 05-25-2009, 02:23 PM
Registered User
 
Join Date: Aug 2008
Posts: 436
I'd use the Nygl (sp?) recommened for your application. I'm assuming you are staying R-12? Yes absolutely go with the newer style o-rings (green) when possible.
Flushing-did this car have a bad compressor failure? You can get a general box of green o-rings at harbor frieght for $10.
I've flushed with flushing chemicals and then also used a general clean petro-based product which leaves very little residue. Yes probably more flamable but I've done naptha as it's $10/gallon with success. You could always follow with real flushing solution.
If you've had a bad failure, a screen on the compressor intake would be a good idea from NAPA.
Long evuation time is good. I'd say 2 hrs MIN but 4-12 is better. But, unless you know that the evacuation pump is working well- no leak in hose connections etc.. pretty hard to say. I've got a submicron gauge and I shoot for stability at 200 microns or less. That says nothing is leaking or boiling off still. Definately shut the hose pump connection to the hoses off and it should hold vacuum with no sign of leakage. Check low side reading and wait 1/2-1 hr and it should be the same.
I ussually replace the switches, but that is down time and acess to recovery aquipment. Distribute your total oil charge within the system as an R4 compressor doesn't have a sump.
If you have dry nitrogen- you can use it and leak detect easily. I've used soapy water with glyerin added many times.

M
Reply With Quote
  #13  
Old 05-25-2009, 02:28 PM
Registered User
 
Join Date: Oct 2005
Posts: 4,263
For Nylog, you need to use the one that is for your intended refrigerant. The green o-rings are fine for 134a or 12 (and others).

10/liter is pretty normal for AC flush. Yes, you can fill the parts with fluid and use air pressure to move it around. Sitting flush agent doesn't do nearly as good of a job as moving agent.

Pulling a vacuum overnight won't help too much. You should get to where you need to be within an hour or two. At these sorts of pressures, your manifold set is pretty much useless. You can hardly tell the difference between 28.8 and 29.8" vacuum. But that's a range of 25,000 microns on an electronic gauge and is very easily seen.

I do not recommend pulling a vacuum and letting it sit overnight to check for leaks. This is because the procedure will ruin your dryer if you do have a leak, and you'll need a new one for the next check.
Reply With Quote
  #14  
Old 05-25-2009, 02:55 PM
mobetta's Avatar
(Oo{-I-}oO)
 
Join Date: Mar 2006
Location: minnesota,hey.
Posts: 1,841
thanks for the tips. I plan on using R12 freon. the system held pressure fine the last time around, even w/ a mickeymouse repair on one rubber line. the failure was the compressor- it started rattling and I removed it from service before black death could result(i think)

would it be bad to flush now,(exp valve forward- unhook lowside @ compressor , and highside at comp, too??????) and do the compressor, valve and (lastly)drier next week- or do it all at once- I plan on charging away from home, so I want to do as much work here as possible.
__________________
1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.
Reply With Quote
  #15  
Old 05-25-2009, 03:01 PM
Registered User
 
Join Date: Oct 2005
Posts: 4,263
Don't uncap the new dryer until you are ready to evacuate and charge the system.

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 05:23 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page