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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #561
So the saga continues today. My AC is getting worse and worse. I'm now really thinking its the expansion valve. Or really not the expansion valve but I think the little screen before the expansion valve is clogged with debris. Possibly from the Aluminum tubes I had welded and couldn't see inside of.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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Discussion Starter #562
I just finished fabing up the mandrel bent tubes for the windshield washer. The welder came to weld them. I showed hing the cooling system expansion tank and told him his welds would be judged against that. He was going to weld it in my shop with my equipment but after I showed him the tank he said I better take it home. Tomorrow I should have it. Hopefully it will be welding porn.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #563
Just completed a test of a float sensor. Unfortunately all I have is the bottom half of the tank that I cut off. But I was successfully able to drill a hole in it widen it out about 2mm with a flap wheel on a die grinder and install it with no leaks. The float sensor is from a 2004 Acura so I hope Acura and MB both have the same circuit logic, switch closed when full vs switch closed when open.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #564
Expansion valve out and everything is clean, So the only other possibility I could think of is I got URO'd. I was able to find a 4 Seasons one from FPC Euro but they haven't shipped yet, so I'm hoping they are still available, because Autohauz and Peach parts only carry URO. Otherwise I can get a Mahl from the UK for $30+ $90.00 shipping.
 

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1983 380 SL
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3,032 Posts
Expansion valve out and everything is clean, So the only other possibility I could think of is I got URO'd. I was able to find a 4 Seasons one from FPC Euro but they haven't shipped yet, so I'm hoping they are still available, because Autohauz and Peach parts only carry URO. Otherwise I can get a Mahl from the UK for $30+ $90.00 shipping.
What refrigerant are you using?
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #566
Guess what just came in as I was writing the last post.

Why am I Scared. Looks exactly like the URO one except for the markings on the top. And of course Made in China.
What refrigerant are you using?
R134a
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #568
You should try Enviro Safe. I coumd't believe how cold the air comming out of my vents was when I charged the system with Enviro Safe.
I have heard good things about it. Right now I have a problem with very low lowside pressure. No sense trying anything else until I get that straight.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #569
New expansion valve is installed, Some re-plumbing and wiring was done . I now wait for one fitting to be delivered tomorrow. I wont have much time because I have to go to NY Sunday. Hopefully I will get a good charge in it and some decent test time. Fingers crossed.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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Discussion Starter #570
Got everything installed and up an running. Some good news some bad news. On first attempt the copper cone seal was not seated properly and leaked immediately. I was always afraid of this happening and this time it did. I hope I didn't cause a scratch in the sealing surfaces on either the TXV or Evaporator. So far I cant detect anything with my leak detector but I need to get ready top get on the road. Replaced the seal and successfully charged 32.5 oz. I didn't want to go any more than that at the moment because that's about 2 oz more than my calculation say is required, but sub cool is still only at 4°. When I get back I may try a bit more.

Ambient temp today was 82°.
High side pressure was 215PSI
Low side pressure was still low at 14PSI
But Duct temp was down to a cool 44°F

I have no idea why the low side will not come up but the high side looks a little better. And I have no idea why its suddenly down to 44° duct temp. I will have a little more testing to do when I get back. I wish I could take the car to NY but there is still a lot of putting back together to do.
 

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1983 380SL, ivory/dk brown, 46k miles, dual roller timing chain. 1986 560SL, red/white, 190K mile.
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6,954 Posts
I watched a video on topping off an AC.
Took these notes:

Pretest:
Rev up Engine to ~2500 rpms
Temp at 49F is excellent

On gauges:
  • Eye protection, gloves
  • Engine off
  • make sure both Lo and Hi are closed on both manifold and cable ends.
  • Lo side will be on the big hose
  • Attach Lo and Hi hoses to AC system
  • Slowly open until gauges move - don’t open all way as you might damage schrader valve
( low gauge might go ~80psi, hi gauge might not move much at all)

Now crank Engine:
  • At idle Lo =~30+, Hi=~175 mild humidity 90+F
  • At 2500rpms Lo=~15psi, Hi=~200+psi
  • Make sure Hi and Lo on manifold are closed
  • Hook up Evirosafe to yellow Charge Hose
  • Can upside down
  • On gauges, purge air out of charge hose by pressing button or loosing connection
  • Never charge on the Hi side. Only charge on the Lo side.
  • Open Lo knob slowly and briefly for a few seconds allow freon to flow.
Rev Engine to 2500rpm and observe gauges:
  • Looking for Hi side to top out at ~225psi, Lo side ~19psi
  • Now check vent temperature at idle and at 2500rpms
  • Observe something like: 49F at idle, 40F at 2500rpms
Now take all the Freon from charge hose:
  • close knob on can
  • turn can right side up.
  • open Lo side on manifold and let it flow into AC system
  • close Lo side on manifold
  • close knobs on hoses ends and remove.
NOTE that as he reved the engine, the Lo side dropped from ~30 to ~15psi

Heres the video:
How To 'Top Off' Your AC System
YouTube
 
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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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Discussion Starter #573
Got the welding finished on my windshield washer tube. Now its time to transfer all this to the real car. But I just realized that all the windshield washer plumbing is not present. I will need to go an archaeological dig through all my wiring and pluming from several cars to find it. Otherwise it will be junk yard time.

The 3 qt bottles are now in stock and I ordered one today.

Next step is scary. I need to drill the big 1.5" hole through my inner fender on the real car.
Attached Thumbnails
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #574
Found all the parts, The new tank came in. Completed all the electrical and plumbing. Now just waiting for the paint to dry on the last bracket I had to make. One problem I had was making the hole for the level sensor too big. It has a slight leak but hopefully some silicon with fix it. Tomorrow I will try it out.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #575
Crash and burn today with the windshield washer. I had a very slight leak yesterday at the level sensor. Put silicone on it and today it was line Niagara falls. Went to test the system to see if it at least worked. No could just be a blown fuse or the WW pump I got out of "Ebola", a car that looked like it was fished from the Marianas Trench. Then I went to open the hood and it was stuck hooked on to the cap for the WW filler. I actually checked to make sure that wouldn't happen on the other car, but different cars have different tolerances. Nothing impossible to fix but about another $100 to 200 in parts and welding and another weekend or so. The only thing I'm most concerned with is the leak, I may have to look into an alternative sensor that goes into the top if I can find one the right size that uses a small hole. The one I have now is from a 2004 Acura. It plugs in from the bottom and obviously making a clean round hole is key. I just ordered some chassis punches which should be able to make a clean hole in plastic. But for the moment this will be on the back burner until after the AC back together and the shop is returned back to some sense of normal.
 

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Premium Member
1983 380 SL
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3,032 Posts
Crash and burn today with the windshield washer. I had a very slight leak yesterday at the level sensor. Put silicone on it and today it was line Niagara falls. Went to test the system to see if it at least worked. No could just be a blown fuse or the WW pump I got out of "Ebola", a car that looked like it was fished from the Marianas Trench. Then I went to open the hood and it was stuck hooked on to the cap for the WW filler. I actually checked to make sure that wouldn't happen on the other car, but different cars have different tolerances. Nothing impossible to fix but about another $100 to 200 in parts and welding and another weekend or so. The only thing I'm most concerned with is the leak, I may have to look into an alternative sensor that goes into the top if I can find one the right size that uses a small hole. The one I have now is from a 2004 Acura. It plugs in from the bottom and obviously making a clean round hole is key. I just ordered some chassis punches which should be able to make a clean hole in plastic. But for the moment this will be on the back burner until after the AC back together and the shop is returned back to some sense of normal.
I also long for the day my shop is returned to some sense of normal. I feel your pain.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #577
Big success on the AC. These taken 81° F ambient 65% RH, using standard test conditions, engine at 2000RPM windows down, blower high, recirc off. Also checked evaporator temp operation. Engine at idle, blower low, windows closed recirc on. Clutch cycled off at 32°F back on at 36° F.

AC is done.
 

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Premium Member
1983 380 SL
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3,032 Posts
Big success on the AC. These taken 81° F ambient 65% RH, using standard test conditions, engine at 2000RPM windows down, blower high, recirc off. Also checked evaporator temp operation. Engine at idle, blower low, windows closed recirc on. Clutch cycled off at 32°F back on at 36° F.

AC is done.
Well done.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,432 Posts
Discussion Starter #579
Well done.
Thanks.

I'm hoping to take it to NY in a few weeks. I still need to check the cooling system to make sure it doesn't overheat with the condenser now in front of the radiator and the added load from AC. That trip should be a good test of it.
 
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