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 08-16-2005, 10:06 AM
KATSCAN's Avatar
look to the cookie
 
Join Date: Aug 2005
Location: Pensacola/south carolina
Posts: 106
Expansion Valve Tweaking

Has anyone heard of tweaking the expansion valve. Open or close it more?
They're spring loaded so I'm not sure it can even be done effectively. I've taken a couple of them out and disassemble them and cleaned them. Back to normal. But could they be better?

__________________
JHaburay

1972 280se 4.5 "princess"
1986 2.3-16v first 100 (099) USA
Reply With Quote
  #2  
Old 08-16-2005, 10:13 AM
1991300SEL's Avatar
Registered User
 
Join Date: May 2003
Posts: 545
I've never done it, but once knew the owner of an independent garage who claimed that he could get 36F vent air from auto a/c systems by "tweaking" the expansion valve and not freeze up the evaporator.

There are those who know and there are those who know more.

Interesting subject.
__________________
'91 300-SEL
Reply With Quote
  #3  
Old 08-16-2005, 02:54 PM
KATSCAN's Avatar
look to the cookie
 
Join Date: Aug 2005
Location: Pensacola/south carolina
Posts: 106
well, I took one of my old xpansion valves and installed it with a modification. It didn't freeze my evaporator but it did not help performance yet. My garage man said to run it a couple of days.

Before the change I was operating at a low high side pressure 25-30; and the hose exiting the evaporator was minor cool; almost lukewarm, must have been good heat transfer in the evaporator and car would cool ok. Also, the line into the evaporator was NOT Hot to touch at all.

With the modification to let more "liquid gas" into the evaporator; I now have a hot to touch line into the evaporator and still a lukewarm exit hose from the evaporator; a high pressure of 65 and not much cooling; maybe less than before. I will remove the valve and check to see if it is still the way I modified it.

I'm getting flow through the drier; yet it is cloudy. I am experimenting with brute force and maybe I'll get lucky. If not, I'll still use the stock setting, but I just have to know.
__________________
JHaburay

1972 280se 4.5 "princess"
1986 2.3-16v first 100 (099) USA
Reply With Quote
  #4  
Old 08-16-2005, 04:16 PM
jbaj007's Avatar
Registered User
 
Join Date: Jun 2001
Location: Santa Monica, CA
Posts: 2,053
You need to become VERY familiar with what "superheat" is; and how to measure it, if you are going to play with the TXV.

You're going to "SLUG" (or have slugged) your compressor. 65psi high side means refrigerant is running right thru.
__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Last edited by jbaj007; 07-28-2006 at 12:19 AM.
Reply With Quote
  #5  
Old 08-16-2005, 06:06 PM
KATSCAN's Avatar
look to the cookie
 
Join Date: Aug 2005
Location: Pensacola/south carolina
Posts: 106
I must admit, i've used superheated steam but i know absolutely nothing about AC. I was just thinking about the xpansion valve being a conduit for the liquid to turn into the gas and become cool very quickly. That is not happening to my system right now with the mod. I might have too much oil in the system, since I have emptied and recharged about 3 times now. Each time 2oz. oil is added. I did fail to mention that this last time I flushed the condenser and evaporator just because it was there; air shop hosed it out the best I could, but I know some of that is in there too. I tend to think that I have a restriction in the xpansion valve or that I have too much oil in the system. It was running half decent before. But not what I want. I want to try to "freeze" that evaporator....thought I was on the right track.
It's my holy grail
__________________
JHaburay

1972 280se 4.5 "princess"
1986 2.3-16v first 100 (099) USA
Reply With Quote
  #6  
Old 08-18-2005, 08:50 PM
KATSCAN's Avatar
look to the cookie
 
Join Date: Aug 2005
Location: Pensacola/south carolina
Posts: 106
No, refridgerant was not passing right thru; there was a restriction in the txv. I want "low superheat" living dangerously; coldest near to the end of the evaporator; a cooler exit line like a cadillace (they use txv too) yes refridgerant can leak through and slug the compressor. But I think there may be more room to play with than we think.
Why are some GM cars spec'd out for desert settings txv? I think one size does not fit all. I am sacrificing my time and may have to sacrifice a compressor eventually, but I think this is very valuble information.

__________________
JHaburay

1972 280se 4.5 "princess"
1986 2.3-16v first 100 (099) USA
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Bad expansion valve symptoms? gpracer Tech Help 43 10-01-2019 02:39 AM
Need Help Changing W124 Expansion Valve Phalcon51 Tech Help 5 09-03-2003 01:11 AM
expansion valve leak? jonhtek Tech Help 2 04-09-2003 10:13 AM
unsteady valve clearances jerryrigged Diesel Discussion 5 01-24-2002 09:55 PM
1985 300D expansion valve question engatwork Tech Help 8 08-13-2001 07:18 AM



All times are GMT -4. The time now is 11:53 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