Low pressure A/C valve
Thread Starter
Super Member
Joined: Apr 2005
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From: Northern Cali
W124
Low pressure A/C valve
I'm looking to retrofit my A/C system to R134 and I need to know the location of the low pressure valve on the A/C lines. Is it the valve on the hose next to the airbox or the valve near the receiver drier/accumulator and radiator? Thanks.
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Joined: Dec 2006
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
You may know the following, but I will say it for the benefit of all. In order for the retrofit to be successful you must remove ALL of the old oil then evacuate the system down to 28" vacuum. You will need a vacuum pump to do this. Removing all of the old oil is almost impossible. If the old oil, which is a mineral oil, mixes with new Ester oil it is a countdown to your compressor locking up. This procedure is best left to an aftermarket specialty shop that has experience and all of the special equipment. It's definitely NOT a DIY for the average weekend mechanic.
As my signature states, I am not an expert in most areas, but I am an "expert" in HVAC and refrigeration by occupation.
Thread Starter
Super Member
Joined: Apr 2005
Posts: 800
Likes: 0
From: Northern Cali
W124
Thanks. I am aware of the dangers of retrofitting. I'm having one of the customers from my work who owns his own shop do the evac for me and I'll just supply him the freon and the retrofit valves/nipples.
MBWorld Fanatic!
Joined: Dec 2006
Posts: 1,042
Likes: 1
From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
Cool. I hope it works well for you. This was the primary reason I didn't buy the pre '93 model. I actually like them better because they seem more like a classic Benz to me for some reason. Also, because of the decreased density of R-134A (it takes up more space in the condenser) it works better in more mild climates than in extremely hot places. If you are in northern California, it should work fine. Please let us know if you have any issues.
