ok, you have a CHARGING station. test for leaks under PRESSURE NOT VACUUM!!!!!
vacuum is a very poor medium for testing leaks. first, it will not SHOW you where the leak is... second it will draw in moisture and non condensibles into your system ruining your new drier. ALWAYS TEST FOR LEAKS WITH PRESSURE!!!!!!YR(@Y*(@$^#(
third, it is VERY close to atmo pressure, only 14.7 MAX pressure difference! pump it up with 100 psi of dry air/Nitrogen or 134 gas and look for a leak. and find it with bubbles! a vacuum test will only show you that it's not holding. it won't tell you where the leak is!!!!!

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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!

All the temp switch does is operate the aux fan.

If the part looks like this:
http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2F10VABWU2FZ0QZ9I9&yearid=1980%40%401980&makeid=MB%40%40MB%40%40X&modelid=300%2DD%2D002%40%40300D&catid=R%40%40Climate+Control&mode=PA&subcatid=R1055@@A%2FC+Temp%2E+Switch&source=www.peachparts.com&clientid=catalog.mercedesshop
it's not a factor in the integrity of the refrigerant system. It just "bolts on" externally to the drier.

Yup...fill it up before the vacuum goes and you have to pull it all over again.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

The system held the same In HG vacuum overnight, so that probably means there's no leaks. I would try to charge it with nitrogen and really find if there are leaks or not, but I'm going to college tomorrow. Next year, I'll probably replace the condenser with a parallel flow one, and do a few more A/C things. I could have my A/C shop charge it with nitrogen, if they have it, to really find leaks. I'm really out of time though...

Tangofox, that looks like the one I have, or used to have. Thanks for describing what it does.

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1980 240d
1999 SL500

it's MUCH faster to test for leaks with pressure. you can do it in an hour. instead of overnight.
are you putting 12 or 134 in? if you are in a hurry. it's best to pull a vacuum, and put a good 100psi of 134 in. and just watch the gauge for movement. if it moves. start checking connections with bubbles and look for the leak. if it's stable. dump it, and pump it back down then charge with the correct amount of refrigerant.

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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!

I'm putting r12 in, with mineral oil. I don't have the retrofit port on the low side for the r-134a anymore, I don't think I could charge it too much without the engine on and compressor running. I'm going to put the new drier in, pull a vacuum for a few hours, then recharge with r12. Or, I could just drive down to the A/C shop and see if they could pump it with nitrogen and find the leaks that way.

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1980 240d
1999 SL500

Put 4oz oil in the drier, an odd ounce in other lines, the rest in the suction hose for the compressor. Drawing a vacuum now for a few hours and I'll turn the compressor by hand, then start charging freon. Stand by for results...

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1980 240d
1999 SL500

Success, very cold r12 A/C. 4oz of oil in the drier and 4 oz in the compressor suction line, turned the compressor more than 10 times by hand. The delco compressor is the way to go for new r4 compressors, it's quieter and smoother than aftermarket r4's. The guys at the A/C shop charged it for me because my charging station is confusing. It had 30 in HG of vacuum when the guy charged it with r12. The A/C is much colder at idle with r12 than ever blew out of the vents with r-134a. I'm very happy, and I saved a bundle doing it myself too. Thanks for everyone's help, I definitely couldn't have done it without your posts.

My evil servo is manipulating the heater valve though . Sometimes not enough vacuum reaches it, and it blasts hot air. Hopefully that won't happen on the road tomorrow. I think it's a low vacuum issue. Waiting a while or moving the temp dial up and down seems to correct it.

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1980 240d
1999 SL500

Please provide the P/N for the Delco compressor that you purchased. Where did you purchase it?

Thanks

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Blair Tyson
1985 300D
300,000 + miles

On second thought, let's not make the OP go through this a THIRD time by posting a source that might not be hosting a great internet resource used by us all!!!!

Derburger - Thanks for sharing and congratulations on the initial success and best wishes for a great academic year.

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83 300d - 390k

Ditto

Good job! I can tell ya there is very little I have done on these cars that has given me as much victorious satisfaction as fixing the AC. (so far so good ). You might consider getting a sniffer - I got one for $75 new in the box with my vacuum pump and flush kit. I tested it on the spent freon cans, and confirmed that it signalled, then took it to every joint I opened with the AC running to look for any leaks.


btw - Robinaire flush kit is CRAP! the valve was not the proper size....ended up renting from AZ.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

The HECAT flush kit is nothing short of awesome. But it is expensive at just north of $250.

Definitely the best thing I've done to the car by far is fix the A/C and return it to r12. The servo worked great on the long drive over. I had the A/C set at 72-76 and I needed to shut it off at times because it was too cold.

I couldn't find an AZ that rented out vacuum pumps or flush kits. I had no problems with flushing with hoses though. I used a 3/8 fuel hose to flush the evaporator, and a larger coolant hose for the condenser. Got every hose clear in a few hours. I might invest in a sniffer off of eBay in the non-hot months if I do more A/C work next season. I could install a parallel flow condenser, an upgraded fan and clean the evaporator. Or I could get a used one off a garage that's downsizing their r12 service, like how I got the charging station. Thanks for the academic year well wishes, I hope so too. I don't want to be wrenching on the MB instead of studying, but we'll see about that .

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1980 240d
1999 SL500

When I flushed my 300SD, I used pressurized spray bottle. We don't by brake/parts cleaner by the can in our shop. We buy a 55gal drum. The techs have these 16-20oz bottles that you fill then use an air hose to pressurize. I attached a small rubber fuel line to the spray tip and filled the condenser & evaporator. It 4 times for each before the exiting streams (used a blow tip connected to an air hose) were clean. It's been 4 months since the compressor replacement and all is well.

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Sharing my partner's 2012 Forte 5dr SX til I find my next 123 or 126..
-
Do I miss being a service advisor ???

Derburger - Thank's for all the info in this thread. I'm copying you right now, minus some errors and with a few of my own.

I ordered a flush gun after trying to make my own flush setup and getting a face full of flush.

That expansion valve is a serious PITA. Getting some crowfoot wrenches tomorrow, as recommended by the factory manual. It calls for 17, 19, 22, 24 crowfoot wrenches, so I'll get the whole set.

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'82 300SD 351k