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#61
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Yes pulled vacuum for 1 hour |
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Great thread, and very timely for me.
I want to upgrade my 1982 300SD ( W126--Gen1) as much as I can while I have it in the shop. What pieces do I need from my 1991 300SE (W126--Gen2) ? I already grabbed the condenser. I plan on new compressor, receiver-drier, and expansion valve. What is the best choice for compressor? Do I need a mounting kit? I plan on using R134 because it is easily available, but if R12 is required to get it really cool in the Mid Atlantic's high heat and humidity--tell me now. ( I have R134 gauges and a vacuum pump) Anything else to know?
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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags |
#63
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The condenser is an unknown. It may or may not fit, the only way to find out is try it and see. You will need custom hoses to make it work. You might be better off building a parallel flow condenser to fit your existing space. You should transfer the dual aux fans from your 1991. They will fit the existing space, but you'll need to transfer over the rod that the horns mount to. Depending on whether the holes are pre-drilled in the radiator crossmember or not, you may need to do some drilling for some bolt holes. The upgraded condenser, compressor, and aux fans should do fine with R134a. The condenser and the puny aux fan are the primary limiting factors in the W123's and Gen I W126's. The evaporator and HVAC box are largely the same between the Gen I and Gen II, although the Gen II's have a much more powerful blower.
__________________
Current stable: 1995 E320 149K (Nancy) 1983 500SL 120K (SLoL) Black Sheep: 1985 524TD 167K (TotalDumpster™) Gone but not forgotten: 1986 300SDL (RIP) 1991 350SD 1991 560SEL 1990 560SEL 1986 500SEL Euro (Rusted to nothing at 47K!) |
#64
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I run R134a and tested my vent temps yesterday: Vent: 46F Outside: 82F Humidity: High Low interior fan speed Good fan clutch (Engine doesn't go above 90C in traffic at 80F outside) Except for the R134a everything else is stock When the sky is cloudy or at nighttime I have to have a slight heater running with the a/c because it just gets too cold. |
#65
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Temp Wheel: ~70F (border where white meets blue) Vent: 46-48F Outside: 86F Humidity: High (hazy because it stormed last night) Sun: High Fan speed: Auto (running med-high to med-low after cabin pulled down) Car sat in direct sunlight from 10:30AM - 4:30PM. Interior hot to the touch. Was cranking out cold by the time we'd navigated the feeder road and gotten on the Interstate.
__________________
Current stable: 1995 E320 149K (Nancy) 1983 500SL 120K (SLoL) Black Sheep: 1985 524TD 167K (TotalDumpster™) Gone but not forgotten: 1986 300SDL (RIP) 1991 350SD 1991 560SEL 1990 560SEL 1986 500SEL Euro (Rusted to nothing at 47K!) |
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[QUOTE=Diseasel300;4047164]Your 1991 compressor won't fit your 1982 under any condition. You need a Sanden conversion from Klimakit or forum member Rollguy if you want to delete the idiotic R4.
Thanks for info---that was about what i had assumed, but confirmation is always good. Yes, I was not planning on using the compressor. I already got the dual fan assembly from the '91. It looks like the mounting holes are there.
__________________
1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags |
#67
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Quick question, why there is R134 A sticker on the expansion valves ? are there specific valves for R12 and R134 ? I thought the expansion valves are designed for any type of refrigerant
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#68
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Expansion valves have different spring rates in the powerhead and different orifice sizes for different gasses. R12 is a larger molecule and runs at a lower pressure than R134a. As a result, R12 has a weaker spring and a larger orifice for the same capacity compared to R134a. You can run R134a on an R12 expansion valve, but you lose a fair bit of capacity in the system. If you run R12 on an R134a expansion valve you will run low suction pressure and can ice the coil (along with reduced system capacity).
It's a big reason why I constantly beat the dead horse of "always change the expansion valve" when redoing the A/C system or converting to R134a. It matters. R12 was banned by the Montreal Protocol in the early 1990s and you won't find service parts for R12 systems anymore. If you plan to run R12, you must run the original expansion valve, not a replacement which will be for R134a.
__________________
Current stable: 1995 E320 149K (Nancy) 1983 500SL 120K (SLoL) Black Sheep: 1985 524TD 167K (TotalDumpster™) Gone but not forgotten: 1986 300SDL (RIP) 1991 350SD 1991 560SEL 1990 560SEL 1986 500SEL Euro (Rusted to nothing at 47K!) |
#69
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New Genuine Mercedes-Benz Valve A/C - Expansion 126830038464 OEM Condition: New Brand: Mercedes-Benz Warranty: Lifetime Manufacturer Part Number: 126-830-03-84-64 Fitment Type: Direct Replacement Other Part Number: 126830038464 Superseded Part Number: 1268300384 |
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Diseasel300 - wow; you are really a fount of information. Have never seen that explanation about R12 vs 134a. Now I understand a bit more.
Thanks for that. |
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__________________
Current stable: 1995 E320 149K (Nancy) 1983 500SL 120K (SLoL) Black Sheep: 1985 524TD 167K (TotalDumpster™) Gone but not forgotten: 1986 300SDL (RIP) 1991 350SD 1991 560SEL 1990 560SEL 1986 500SEL Euro (Rusted to nothing at 47K!) |
#72
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If the charge is low, or the wrong metering device is installed, the head pressure does not build adequately to condense the gas to a liquid. That is where you get the flashing sight glass and poor cooling performance, the expansion valve is open too far to allow head pressure to build sufficiently to condense the gas due to a low volumetric charge. On a very hot day with high humidity, these systems will run a 250-275PSI head pressure vs 200-225PSi on R12. Converse to popular opinion, you need the pressure and you need the heat in the system to do work. The people who stack 2 parallel flow condensers on top of each other are defeating the purpose of the the condenser. The first one condenses the gas, the 2nd one is acting as a liquid receiver, the result being a gross overcharging of the system and very poor cooling performance in cooler or temperate weather. W123 and Gen I W126 cars need an updated condenser to run R134a, they were barely adequate to run R12. The Gen II's are a different story, no upgrade required. The stock system will handle it just fine with a replacement expansion valve and the correct oil.
__________________
Current stable: 1995 E320 149K (Nancy) 1983 500SL 120K (SLoL) Black Sheep: 1985 524TD 167K (TotalDumpster™) Gone but not forgotten: 1986 300SDL (RIP) 1991 350SD 1991 560SEL 1990 560SEL 1986 500SEL Euro (Rusted to nothing at 47K!) |
#73
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__________________
To see my 129 parts for sale visit: http://stores.ebay.com/The-Mercedes-SL-Store John Roncallo |
#74
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Currently just using aftermarket replacement which I assume are designed for R12.
__________________
To see my 129 parts for sale visit: http://stores.ebay.com/The-Mercedes-SL-Store John Roncallo |
#75
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I don't know on the 107s. My 500SL has had the A/C broken since 1998 and I've never torn into it to repair it. The front seal on the compressor is blown, any gas you dump in sprays right back out. I should get off my butt and fix it so it gets used more. I've never laid hands on anything on that system other than the charging ports, so I'm not sure if they use the block-style expansion valve, or the old-school bulb style.
__________________
Current stable: 1995 E320 149K (Nancy) 1983 500SL 120K (SLoL) Black Sheep: 1985 524TD 167K (TotalDumpster™) Gone but not forgotten: 1986 300SDL (RIP) 1991 350SD 1991 560SEL 1990 560SEL 1986 500SEL Euro (Rusted to nothing at 47K!) |
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