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  #1  
Old 09-19-2015, 02:45 PM
xaliscomex
 
Join Date: Feb 2006
Location: Ventura County, CA
Posts: 383
w126 300sel Expansion Valve

How accessible is the expansion valve on my 1988 300sel (w126).
Will removing the cluster give me access to the expansion valve.

My AC runs with R12 freon.
Previous owner mentioned to me that if I replaced the expansion valve I would get better cooling using R12.

I had the compressor replaced a few years back along with hoses and dryer.
There was an initial problem getting everything to work but hours, so the tech told me, of running or pushing the freon thru the expansion valve made it work.
The tech did mention that a new expansion valve would make my AC super cold but he mentioned that the dash would have to be removed, and that was very intensive work.

I do not have any experience with AC systems other than swapping around parts.

I sometimes think that the tech maybe was not experienced and might have used the expansion valve excuse to explain the lack of cold cold super cold air.

I previously had heard from a forum member that it is important to use the Mercedes Oil for our AC systems. Worth every drop. I don't know why, but thats what was recommended. Don't ask me how the oil is used.

Currently I get about 59 deg F to 61 deg F at the vent while driving at 70 mph. (Outdoor Temp 85 deg F)


Last edited by xaliscomex; 09-21-2015 at 06:34 PM.
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  #2  
Old 09-19-2015, 06:41 PM
Senior Member
 
Join Date: Nov 2002
Posts: 839
the expansion valve is above your right knee. pull the wheel, pull the cluster, pull the knee bolster and trim panel on tunnel. then you can see it. they are a MOTHER to remove. very tight fittings and very tight working space. you need a wrench to hold the valve still as you wrestle with the fittings. you need line wrenches for the 4 nuts on 4 pipes, soft, bendable pipes. especially on the evap. good luck, chuck.
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  #3  
Old 09-19-2015, 07:30 PM
Home appliance genius
 
Join Date: Jul 2009
Location: cleveland
Posts: 1,160
I replaced one on a 300se I had years ago. You need some crows foot wrenches, and I ended up cutting one of my regular wrenches to make it fit.
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  #4  
Old 09-19-2015, 09:08 PM
xaliscomex
 
Join Date: Feb 2006
Location: Ventura County, CA
Posts: 383
ouch...but the dash can stay in place, right?
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  #5  
Old 09-19-2015, 10:25 PM
Home appliance genius
 
Join Date: Jul 2009
Location: cleveland
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Quote:
Originally Posted by xaliscomex View Post
ouch...but the dash can stay in place, right?

Yes, I removed the speedo cluster, and moved a few other minor things. I slid the seat back all the way and got it replaced in under 2 hrs.

Going by my foggy memory:

1 - the crow foot wrenches are a must.
2 - the wrench that I cut in half was important, bordering on must have.
3- get all 4 nuts half way in before you tighten.
4 - I'm 5-7' and 135lbs. That really helped.
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  #6  
Old 09-20-2015, 04:43 PM
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It is one of the hardest (awkward) things to change out. You essentially need to be on your back with your head against the gas pedal. Forget it if you depend on bifocals.
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  #7  
Old 09-20-2015, 10:46 PM
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Join Date: Mar 2007
Posts: 159
Check the recirculation pods. If they are inop, it can cause high discharge temps.
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  #8  
Old 09-21-2015, 07:13 AM
Hirnbeiss's Avatar
ich fahre, also bin ich
 
Join Date: Mar 2002
Location: South Florida
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Here's a good guide:
Removal and Replacement of Expansion Valve
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  #9  
Old 09-21-2015, 06:33 PM
xaliscomex
 
Join Date: Feb 2006
Location: Ventura County, CA
Posts: 383
Expansion Valve

Quote:
Originally Posted by Hirnbeiss View Post
Very good write up, thanks

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