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 > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 05-15-2008, 03:52 PM
EZ
 
Join Date: Jul 2006
Location: Sacramento, California
Posts: 107
When recharging R134a do I need to replace drier?

1988 300 SEL
It was converted to R134a before I came along. A/C has been gradually getting warmer over the past two years and I figure it's time for a recharge. Did a lot of reading here and other sites about AC systems but still have a couple of questions.
1. If I am just recharging is that considered an "open system", in which case everyone seems to recommend replacing the drier. Mercedes I believe recommends replacing the drier when the system is open and the drier is more than 5 years old. Conversion on this car was done in '99 so I assume it has not been replaced since then. In sum, if I recharge only, should I replace the drier?

2. If I do replace the drier, is that something I can do without vacuuming out the system? As a corollary question, do you need to vacuum out the system every time you recharge

My plan was to replace the drier, since it is 9 years old, and to then recharge with R134a. I just don't want to blow myself up or kill baby seals or whatever badness happens when this stuff gets released. Thanks.

__________________
Eric Zacharias

'88 300 SEL
'64 Ford Falcon
'99 Infiniti QX4
Reply With Quote
  #2  
Old 05-15-2008, 03:55 PM
TX76513's Avatar
Platinum Member
 
Join Date: Apr 2003
Location: Brandon, Mississippi
Posts: 5,203
If you are going to open the system its a best practice to replace the drier. If you are going to just pump it down and add more 134 or just adding 134 I wouldn't bother.
__________________
BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif
15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
(o\|/o)
Reply With Quote
  #3  
Old 05-15-2008, 04:17 PM
Registered User
 
Join Date: Oct 2005
Posts: 4,263
If the dryer is original, you definitely need a new one. The old desiccant is not compatible with 134a. The new models work for either R12 or 134a.

If you replace the dryer, you should definitely pull a deep vacuum before recharging. Remove the old dryer, and try to extract as much oil as possible so you can measure it. Put in the new dryer the larger quantity of what you got out, and what the FSM says for the dryer replacement, then quickly attach the dryer and start the vacuum pump.

You do not need to vacuum the system for a top-off of refrigerant, but you should definitely vacuum it any time the system is open to the atmosphere, no matter how short of a time it is exposed. If you're not flushing, try to keep the time that the system is open to an absolute minimum. The oil absorbs water and turns acidic.
Reply With Quote
  #4  
Old 05-15-2008, 10:15 PM
EZ
 
Join Date: Jul 2006
Location: Sacramento, California
Posts: 107
I think the system still has some charge to it. If I start out by disconnecting the drier will that release r134 into the atmosphere? Do I need to take any precautions when disconnecting the drier?
The order then would be, disconnect drier, install new drier, vaccum out system, and then refill with r134.
__________________
Eric Zacharias

'88 300 SEL
'64 Ford Falcon
'99 Infiniti QX4
Reply With Quote
  #5  
Old 05-15-2008, 10:42 PM
carnut's Avatar
Registered User
 
Join Date: Jul 2006
Location: Stockton California
Posts: 637
The system is under pressure. It will freeze your hands by simply disconnecting the drier!! So, remove freon with a recovery machine, then remove/replace drier. Then vacuum system down, then add 134. If 134 is low, it has a leak somewhere. When you add the 134 add leak detection dye to the system and check for a leak in 2 weeks.
__________________
81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.
Reply With Quote
  #6  
Old 05-16-2008, 10:30 AM
RichardM98's Avatar
Registered User
 
Join Date: Oct 2007
Location: SoCal
Posts: 651
Quote:
Originally Posted by carnut View Post
The system is under pressure. It will freeze your hands by simply disconnecting the drier!! So, remove freon with a recovery machine, then remove/replace drier. Then vacuum system down, then add 134. If 134 is low, it has a leak somewhere. When you add the 134 add leak detection dye to the system and check for a leak in 2 weeks.
+1
Reply With Quote
  #7  
Old 05-21-2008, 11:25 PM
mr300ce's Avatar
Old Cowboys Never Die !!
 
Join Date: May 2008
Location: Mojave Desert, Ca.
Posts: 45
Simply solution.

Bring it to my shop, where I charge $49.95 service fee plus the cost of the freon added.

We recover, measure whats in there, check for leaks, test the operation of the system, and ad some dye for finding future leaks.

Most customers get out of there for about $80.
__________________
1990 300CE. Garage kept all its life. Looks & Runs Like New. Everything works. White w/Palomino int. Pioneer 12 CD player in the boot. 17" Enkei LX-F Chrome wheels w/Falken Azenis ST-115 225-45 tires. Tinted windows. Black sports grill w/Euro clear front lamps.
Reply With Quote
  #8  
Old 05-21-2008, 11:46 PM
Registered User
 
Join Date: Apr 2008
Posts: 84
Quote:
Originally Posted by ericzacha View Post
1988 300 SEL
It was converted to R134a before I came along. A/C has been gradually getting warmer over the past two years and I figure it's time for a recharge. Did a lot of reading here and other sites about AC systems but still have a couple of questions.
1. If I am just recharging is that considered an "open system", in which case everyone seems to recommend replacing the drier. Mercedes I believe recommends replacing the drier when the system is open and the drier is more than 5 years old. Conversion on this car was done in '99 so I assume it has not been replaced since then. In sum, if I recharge only, should I replace the drier?

2. If I do replace the drier, is that something I can do without vacuuming out the system? As a corollary question, do you need to vacuum out the system every time you recharge

My plan was to replace the drier, since it is 9 years old, and to then recharge with R134a. I just don't want to blow myself up or kill baby seals or whatever badness happens when this stuff gets released. Thanks.
No offense, but let a pro fix it.

Unless you have the right training, tools and equipment you could hurt yourself easily.

Not to mention it's highly illegal to vent R134 or R12.
Reply With Quote
  #9  
Old 05-21-2008, 11:50 PM
Registered User
 
Join Date: Apr 2008
Posts: 84
Quote:
Originally Posted by ericzacha View Post
I think the system still has some charge to it. If I start out by disconnecting the drier will that release r134 into the atmosphere? Do I need to take any precautions when disconnecting the drier?
The order then would be, disconnect drier, install new drier, vaccum out system, and then refill with r134.
Leave it alone. I wish R134a wasn't sold over the counter, what is going to happen when somebody who doesn't know what's going on hooks a can of R134 to the high side of the system?

Unless you want a serious case of frostbite, don't touch it. You don't go around disconnecting a/c lines without the proper equipment.

This is why R12 got banned, and R134 is going to be banned soon. People who don't know what they are doing are venting gas into the atmosphere and getting themselves hurt.

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 03:33 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page