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 02-20-2010, 03:03 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: Eastern TN
Posts: 20,841
AC compressor replacement help needed

I'm replacing the AC compressor of my 87 300D because the compressor leaks refrigerant. The compressor still works, a trusted shop don't think it sent shrapnel through the system. My plan thus is to replace the compressor and have the system recharged with R-12.

There's a list of items I can change (expansion valve, drier, etc.) but I'd like to know what I should change.

Questions:

1) A shop I trust says there's no need to replace the drier if the system is clean and hasn't been exposed to moisture. What are the pros and cons other than cost?

2) Ditto the expansion valve?

3) Should I replace other system seals, at least the ones in the engine bay?

4) Which are better - green o-rings or black o-rings?

5) There is grime around the low pressure Schrader valve. I clean the area and it's grimy again by the next oil change. Should I replace the Schrader valve?

Thanks,
Sixto
87 300D

Reply With Quote
  #2  
Old 02-20-2010, 03:12 PM
Registered User
 
Join Date: Oct 2005
Posts: 4,263
If the system is evacuated and then flooded with dry gas (such as nitrogen), you won't be adding much water to the dryer and reusing it is almost certainly fine, if the work is done quickly. But if you're taking it apart and replacing any other system seals, replace both the dryer and TXV.

If you're sticking with R12, you can use green or black o-rings. Be sure to use the appropriate lubricant for R12.

The service fitting cap should seal the low pressure port. You can replace the valve core, but also ensure that your cap seal is in good shape.
Reply With Quote
  #3  
Old 02-20-2010, 05:36 PM
Jeremy5848's Avatar
Registered Biodiesel User
 
Join Date: Mar 2006
Location: Sonoma Wine Country
Posts: 8,402
I don't know the parts costs involved, but once the system is evacuated of Freon and you're doing the work yourself, I would replace everything I could easily access (i.e., NOT the evaporator) except the condenser. Make sure the condenser fins are clean, though.
__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970
Reply With Quote
  #4  
Old 02-20-2010, 06:55 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: Eastern TN
Posts: 20,841
That's another angle to my question - should I replace a couple hundred dollars worth of hoses? If not, should I touch fittings that have been happy for 23 years to replace o-rings?

Thanks,
Sixto
87 300D
Reply With Quote
  #5  
Old 02-20-2010, 07:46 PM
oldiesel's Avatar
Registered User
 
Join Date: May 2007
Location: florida
Posts: 677
If your system is still holding pressure i would not go taking apart connections that are NOT leaking on the chance that they will not leak when reassembled with new o rings these are old cars and disturbing things can open a big can of worms.If the hoses look rotten a good A/C shop can replace the hose part and reuse the pipes for small money compared to MB prices. Don
__________________
Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles
Reply With Quote
  #6  
Old 02-20-2010, 08:07 PM
Hit Man X's Avatar
I LOVE BRUNETTES
 
Join Date: Sep 2004
Location: FUNKYTOWN
Posts: 9,087
Thumbs up

The dryer and exp valve are so inexpensive, why not?

I have also been taught that whenever the system is opened, you replace the accumulator/dryer.

Yes, replace the o-rings. I am sure the hoses are fine.

Schrader valves are also inexpensive, I would replace.

Test the temp sender on the head, if questionable replace. I would get the red one as it kicks the aux fan on soonest.

I would consider a flush so you can have the correct amount of oil in the system upon compressor install.
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
Reply With Quote
  #7  
Old 02-21-2010, 12:04 AM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
You should not be trusting that shop..
Everyone who knows anything about AC systems knows that if you open the system at all you must replace the receiver dryer... there is no question about that... go to another shop for the rest of your AC work.

Read Hit man X's post and follow it closely... those are all industry standard safe answers...
except that assumption about the hoses... that will be determined by your pressure test with nitrogen and R22 before you do your vacuum immediately before filling your system ...
The part about flushing with regards to the amount of oil in the system is very important.. that is the only way you can know that you have the proper amount ..and that it is clean.... and you can not just add... because too much oil is very bad also...


Last edited by leathermang; 02-21-2010 at 12:24 AM.
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 09:06 AM.


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