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  #1  
Old 08-14-2020, 04:41 PM
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W123 Factory Aircon rebuild using new MB R4 Compressor

Greetings!

After much research, I've decided to go with a new R4 compressor from Mercedes for my 84 300D NA Automatic. Sells new from Mercedes for around $720 with a 2 year warranty. It would cost me a similar amount to import a Sanden and corresponding mounting kit to the UK and saves me the hassles of fabricating hoses to accommodate RHD clearance issues. We don't really use air-conditioning in the UK for more than a 2-3 weeks a year, so the major benefits of the Sanden solution (economy, power drain etc.) are minimized to some extent.

I have 2 questions I hope someone with experience doing this can help with:

A. I plan on replacing the following. Condensing radiator was newly installed a couple years ago and is unused. Am I missing any must replace parts?

1) Aircon Receiver dryer - Part #1238300683

2) Aircon Compressor - Part #0002304711

3) Aircon Expansion Valve - Not sure what the correct part number is.


B. Any sequence of what to flush/ oil/ install etc.?

Many thanks in advance!

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  #2  
Old 08-14-2020, 05:43 PM
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Wait a minute. Try to contact Rollguy on here and get a "kit" to convert it to a new, modern Sanden compressor. Replace it, install a parallel flow condenser and run it on r134 and don't look back. Rollguy builds and supplies a high quality bracket assembly. I've installed Sanden units on three different 123 cars with no issues.

I'd be hard pressed to purchase a new R4 compressor from Mercedes Benz but that is just me.
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  #3  
Old 08-14-2020, 05:59 PM
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The Sanden kit requires hose fabrication for Right Hand Drive models due to clearance issues. It's also no cheaper to purchase the compressor + kit, and import them.

I had looked into the Klima kit which I believe is similar to Rollguy's. Just looking for the easiest solution and the R4 seems more straightforward.
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  #4  
Old 08-14-2020, 06:28 PM
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I forgot about the steering wheel location.
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  #5  
Old 08-14-2020, 08:13 PM
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I purchased a brand new R4 compressor for less than $200. Four Seasons brand, it's been working well for two years. Came with a 2 year/24000 mile warranty.
Are there less expensive brand new R4's available to you in the UK besides the dealer?
If not maybe it would be worthwhile to import from the USA? I ordered from rock auto.
I'm happy with the air conditioning performance this hot humid summer here in NYC. It's adequate using R12 refrigerant.
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  #6  
Old 08-15-2020, 01:43 AM
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Join Date: Oct 2014
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Quote:
Originally Posted by Screwdriva View Post
Greetings!
[...]
I have 2 questions I hope someone with experience doing this can help with:

A. I plan on replacing the following. Condensing radiator was newly installed a couple years ago and is unused. Am I missing any must replace parts?

1) Aircon Receiver dryer - Part #1238300683

2) Aircon Compressor - Part #0002304711

3) Aircon Expansion Valve - Not sure what the correct part number is.


B. Any sequence of what to flush/ oil/ install etc.?

Many thanks in advance!

I'd replace all the hoses. They're ancient.
If you're sticking with R12, you may have trouble finding the correct expansion valve. The ones for sale now are made for 134a.
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  #7  
Old 08-15-2020, 04:13 AM
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The r4 compressor was a GM Unit,Mercedes does not make this,not only that many brands were being made in Mexico,and yes Mercedes out sources from a number of countries,so the compressor is re-boxed and sold to you for 3x the money.
These compressors are weak,expected life 5years in hot conditions.
The front bearing plate is upside down,Mercedes never fixed,there is a x marked on plate
to denote up when installed or front bearing will be starved of oil.
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  #8  
Old 08-15-2020, 07:33 PM
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When replaced my ac compressor this summer and installed everything I did the following:

Bought a complete AC o-ring set (you'll want to replace every single o-ring in the system)

Bought a small bottle of PAG lubricant for the compressor and o-rings (I went with sanden check what lube your compressor will take)

new receiver dryer

new high pressure switch

new fan switch on receiver dryer

new expansion valve (very easy to replace on a w123)

I also completely flushed the evaporator in the car with just generic ac flush sold at the autoparts store as well as the condenser on the radiator.

Replaced the electric fan (my old one did not work when jumped directly to 12v)

I would inspect your hoses. If they don't have any cracks when you bend them I wouldn't get them all replaced / remade. I used my original hoses and switched to r134 and everything has been working well all summer so i don't think I have any leaks.

Side Note!
Be sure your cooling system is in good health. Every single part is new in the cooling system of my 82 240D with the exception of the radiator that seems to be in excellent shape and it still will heat up in drive at idle for an extended period of time (say 15 mins). My engine runs right above 80C when the ac is off but with it on depending on traffic and stopping (at a drive thru say) it will creep up to 100C and sometimes a touch higher which makes me anxious enough to turn off the ac for a few mins so it cools back down.
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  #9  
Old 08-19-2020, 02:35 PM
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I have done as all of you have suggested. I purchased the Klima cool kit with new receiver dryer, o-rings, pressure switch and expansion valve. Sanden 4272 compressor also on the way.

No going back now!
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  #10  
Old 08-19-2020, 03:24 PM
wrench dropper
 
Join Date: Oct 2014
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Quote:
Originally Posted by Screwdriva View Post
I have done as all of you have suggested. I purchased the Klima cool kit with new receiver dryer, o-rings, pressure switch and expansion valve. Sanden 4272 compressor also on the way.

No going back now!
I think you made the right choice. I finished retrofitting my W123 with a Sanden compressor and R134a yesterday.


If your condenser isn't parallel flow, you'll need to replace it with one that is.


Be sure to flush all the oil out of the evaporator. It's easier if you remove the old expansion valve, drill it out and then reinstall it. That way you can flush through the hoses rather than having it spray all over your interior floor.



If the Klima kit doesn't include a mod for the aux fan, you may want to look into getting one or making one. It's a relay that makes the aux fan come on whenever the compressor is on, rather than being triggered by a temp sensor in the dryer.
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  #11  
Old 08-19-2020, 07:24 PM
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I wasn't planning on switching to R134 just yet. We have R24 gas available here in the UK so was hoping to keep the OE condenser I have installed.
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  #12  
Old 08-19-2020, 11:15 PM
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I left my oe condenser installed with the Klima kit and everything functions fine. My ac temps out the vents are around 38*F with ambient temp of 85-90*
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  #13  
Old 08-22-2020, 07:29 AM
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Quote:
Originally Posted by mabbonizio View Post
I left my oe condenser installed with the Klima kit and everything functions fine. My ac temps out the vents are around 38*F with ambient temp of 85-90*
Thanks for this! Did you switch to R134 gas? If so, I'm assuming you left the oil in the compressor as is?
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  #14  
Old 04-02-2021, 06:04 PM
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I was thinking about spending the $750 on the Sanden and custom bracket, but right now Advance has an R4 compressor with a Lifetime Replacement warranty (as long as you replace the drier and flush the system) for $240.
A lifetime replacement warranty on an R4 seems pretty audacious, so I figured I would put it to the test. I'll get at least two for one, worst case scenario.
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  #15  
Old 04-02-2021, 08:58 PM
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Quote:
Originally Posted by 1983/300CD View Post
I was thinking about spending the $750 on the Sanden and custom bracket, but right now Advance has an R4 compressor with a Lifetime Replacement warranty (as long as you replace the drier and flush the system) for $240.
A lifetime replacement warranty on an R4 seems pretty audacious, so I figured I would put it to the test. I'll get at least two for one, worst case scenario.
If you're in a hot and/or humid climate running the AC most of the time unless you run a hydrocarbon blend (e.g. Duracool or Enviro-Safe) or R12, expect to swap that POS out every 3,4 years (5 if you're lucky) running it on R134.

Unless it has been redesigned and the quality improved...in China...

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