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Is It the Compressor?
Year: 1981
Make: Mercedes Model: 300SD Engine Size: 3.0L Refrigerant Type: R12 Ambient Temp: 79degF Pressure Low: 60 Pressure High: 125 I just replaced my R4 compressor with a new (not a rebuilt) Compressorworks compressor, along with the receiver-dryer. I have thoroughly flushed the entire system twice. I also carefully added oil throughout the entire system, including 90 Ml in the compressor. I turned the compressor over by hand for 40 revolutions. The system held a good vacuum overnight. Total evacuation time was 4 hours. When I started adding R12, I noticed that the low side was not going down as I would have expected and the high side did go up as high as expected. There was some cooling, about 5 degrees differential from ambient. One other thing I noticed was that both needles on my gauges were fluttering, something I haven't noticed before. Which brings me to the title of this post: Is it a faulty compressor? Did I do anything wrong in the installation? I have installed about 8-10 R4s and this is the first one that acted this way. Thanks for your help.
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Tom Evans 69 280SE 91K (wish I still had it) 73 220D 98K 78 300D 134K 78 300D 185K 81 300SD 301K (still have) 82 300SD 321K (still have) 84 300D 268K 84 6.2 Diesel GMC Suburban 225K (a whole different story!) |
#2
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Was the car at high idle...
and did you have a fan blowing across the condenser ? Were you installing vapor and into the low side valve ? Are you sure your compressor engaged ? Did you jump the pressure switch to get it to engage or did it due to pressure getting high enough ? Did you have the inside temp control set to max and the high blower on ?
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#3
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Let's hope not!!!
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#4
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Quote:
I start charging vapor through both the high and low sides WITHOUT the engine running. Then I close off the high side and crank the engine and finish charging through the low side as vapor. Compressor is difinitely engaged. I did not have to jump the pressure switch. The temp was set to max cool and the blower was manually set on speed 6. No fan on the condenser. It was 79 degrees ambient.
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Tom Evans 69 280SE 91K (wish I still had it) 73 220D 98K 78 300D 134K 78 300D 185K 81 300SD 301K (still have) 82 300SD 321K (still have) 84 300D 268K 84 6.2 Diesel GMC Suburban 225K (a whole different story!) |
#5
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High low side pressure with fluctuations can be caused by bad or sticky valves.
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#6
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#7
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The combo of not high enough, not low enough and fluctuations sure does sound like a compressor problem.
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#8
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I replaced the suspect compressor tonight with a known-good used compressor. That was the problem. As soon as the compressor clutch kicked in, the low pressure went down and the high pressure went up to the expected values with steady gauge readings. I figure that the suspect compressor had one or more bad reed valves.
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Tom Evans 69 280SE 91K (wish I still had it) 73 220D 98K 78 300D 134K 78 300D 185K 81 300SD 301K (still have) 82 300SD 321K (still have) 84 300D 268K 84 6.2 Diesel GMC Suburban 225K (a whole different story!) |
#9
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Good find. I hope you were able to reclaim the R12 you had charged the system with........
Sure does throw a wrench into things when your NEW part is defective!
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Jimmy L. '05 Acura TL 6MT 2001 ML430 My Spare Gone: '95 E300 188K "Batmobile" Texas Unfriendly Black '85 300TD 235K "The Wagon" Texas Friendly White '80 240D 154K "China" Scar engine installed '81 300TD 240K "Smash" '80 240D 230K "The Squash" '81 240D 293K"Scar" Rear ended harder than Elton John |
#10
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Good, now Jimmy... go back to Pizzachef's thread....
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#11
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Quote:
I was planning to get a new "Compressor Works" R4, new drier, and new expansion valve (that would give me a 2 year warranty buying all three from Autozone). Any one else have a bad experience with the Compressor Works brand?
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Charles 1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html |
#12
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Quote:
Haven't experienced the fine work of the Compressor Works brand. More like Compressor Don't-Work......
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Jimmy L. '05 Acura TL 6MT 2001 ML430 My Spare Gone: '95 E300 188K "Batmobile" Texas Unfriendly Black '85 300TD 235K "The Wagon" Texas Friendly White '80 240D 154K "China" Scar engine installed '81 300TD 240K "Smash" '80 240D 230K "The Squash" '81 240D 293K"Scar" Rear ended harder than Elton John |
#13
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Cr, it may be that some have not specified the correct R4 for the refrigerant they were using...
Check with Tray at Carlisle Auto Air in San Antonio to make sure you are on the right side of the design curve...I think I have posted the correct later serial numbers... Particularly if you are using R134a...
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#14
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just a note. you mention replacing the compressor, the dryer, and the oil.
what about the expansion valve?
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!! 1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere! |
#15
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I've had good luck with Compressor Works in the past. I have one on my other MB. It has worked well since 2004. That's why I wanted another Compressor Works unit. That and the fact that it was $70 less than a new Delphi. We'll see how AutoZone handles it.
Yes, I do recover R12. I wouldn't be working with R12 if I couldn't recover it. My concern now is whether I need to flush the system out again. The oil I drained out of the defective ceompressor was darker in color than it went in, but there was no particulate matter in the oil. Also, should I change out the receiver/drier? (It was replaced along with the Compressor Works compressor)
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Tom Evans 69 280SE 91K (wish I still had it) 73 220D 98K 78 300D 134K 78 300D 185K 81 300SD 301K (still have) 82 300SD 321K (still have) 84 300D 268K 84 6.2 Diesel GMC Suburban 225K (a whole different story!) |
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