Hello Members

I have just completed replacing the evaporator core, expansion valve, receiver drier, new O rings at every fitting and suction hose in my 82 240D. I have pulled a vacuum on the system, and it holds 30 hg for 36 hours. So I think I am ready to charge the system now. I have 2 12 oz cans and 1 14 oz can of r-12, my question is am I supposed to charge these cans as a gas(upright) or as a liquid (up-side-down) on the low-(suction-side)...

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240_Dizzell

74 240D Auto,Beige (Totaled)
82 240D 4-Speed Manual,Gray (Retired) 260,000
97 E300 D Auto, Blue (Current) 240,000
05 E320 CDI Auto,TITANITE RED (Current) 158,000

Always put cans upright, you do not want liquid freon get into the system.
When the can gets real cold this is when you want to dip the can into warm water. Doing this will keep the pressure up in the freon can while its filling.



David
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1985 300D Turbo

You have the concept BACKWARDS.
Don't proceed until I can post a picture of the manual ....

ok,,, here is the warning....

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There are situations where a PROFESSIONAL might use liquid charging to a system.... the engine would be OFF and the liquid would be put into the HIGH SIDE of the system.
Then at some point they would probably switch to the low side and start the engine and fill the remainder that they needed as a gas into the suction side.
WEAR GOGGLES WHEN DOING AC WORK !!!!

It is safer for us to strictly use the vapor charging through the suction side with the engine running......
If you put any liquid refrigerant into the suction side you will most likely break your reed valves in your compressor...
Unlike most of the stuff I say in AC threads.....which comes from manuals...... THIS I know first hand......

I've found that putting the can close to the engine heats it up enough to hurry the process a bit. Otherwise, it seems to take forever.

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1984 300Sd 210k

Former cars:
1984 300D 445k (!!) (Strider) Original (and not rebuilt) engine and transmission. Currently running on V80 ( 80% vegetable oil, 20% petroleum products). Actually not, taking a WVO break.
1993 300d 2.5 275k. Current 120/day commuter
1981 300SD 188k (Hans) Killed by a deer

The operative word in the manual posting is "EXCESSIVELY HOT." Use luke warm water to boil the refrigerant out of the can.

There are some compressors that are more easily damaged with liquid hitting them than others. Don't take any chances though, don't introduce liquid while the compressor is running on any compressor. If the system won't take the refrigerant, use the warm water, don't turn the can upside down.

Good luck,

WOW!

What fantastic advice! You guys are well informed on AC. I can't tell you the number of times I have seen "mechanics" charge the system with the can upside down and to the suction side.

Now I wonder who I can find locally that "knows" what they are doing, since my AC acts like it may need a charge (the pressure switch is not activating the aux. fan).

This may be something else I need to learn to DIY in order to have it done right. I am a little hesitant about doing it the first time, considering that a inexperienced error can cause major consequences.

You are half way between Larry and me....
Run up there and let Larry supervise you the first time... Of course Larry is actually in Oklahoma but won't admit it...

Thanks everyone

your pointers and advice are worth more than a wells-fargo truck.
I forgot to mention that the very first can that I was going to charge into the system is going to be an 3.5 oz OIL CHARGE can
which contains 1.4 oz of oil and 2.1 oz of r-12. The directions on the can say to shake up the can and connect to suction side in upside down position. This being the case, would it hurt the compressor or system to charge this first can this way into the vacuum evacuated system without the motor running. As a matter of fact, I was gonna put the oil charge in and my largest
can (14) oz {can upright} even before I started the motor and engaged the clutch. Any advice or scoldings will be helpful.....

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240_Dizzell

74 240D Auto,Beige (Totaled)
82 240D 4-Speed Manual,Gray (Retired) 260,000
97 E300 D Auto, Blue (Current) 240,000
05 E320 CDI Auto,TITANITE RED (Current) 158,000

I think that the thing to do with the oil charge is to do as you say, putting it as liquid into the vacuum, maybe through the high side only. After you shut off both sides to change cans, turn the compressor several times by hand, without the engine running of course. Then go ahead and give it as much more as it will take into the vacuum on both sides. Once it is taking no more, shut off both valves and again turn the compressor 6 or 8 turns by hand before starting the engine.

Then you can go ahead and charge the rest through the low side of course.

Yes, I'm about as close to being an Okie(God forbid) as I can be. There is actually a guy down the river about thirty miles who used to be a Texan, but the river changed course. He now farms on an island. You would think that this means he is in no mans land, neither Texan OR Okie. Most people don't know it, but Oklahoma begins at the South edge of the water. If you are standing in Texas and put your toe in the water, your toe is in Texas and your other foot is in Texas. Some Texan obviously got snookered on that deal.

Good luck,

Unless someone gets the idea that I'm telling them to charge into the high side of a running system I don't see anything wrong with the procedure. It is common to charge into both sides after pulling a vacuum until the system will take no more refrigerant. Then you start the system and charge normally.

Putting the oil into the high side puts the liquid UPSTREAM from the compressor. Turning the compressor a few turns by hand is simply a precaution.

Have a great day,

That was the question... as a precaution to what ?

Hey everyone,
I've been doing a search on expansion valve replacement and I think I'm going to stop here. Found a lot of useful info but have a question.
When you tighten the refrigerant lines into the expansion valve should you use thread sealant like blue loktite? What is the proper torque?

Also it lost about 3 or 4 charges before I found the expansion valve leak. Do I need to ad ref. oil or is there enough left in the compressor, evaporator, condenser, etc...

The reason you never want to charge liquid refrigerant into a system under vacuum is because the refrigerant will freeze up the system. You would turn the evaporator into a block of ice. It is ok to charge small amounts of liquid into a system above 32 - 33 psi. It would have to go through the evaporator and accumulator before it reaches the compressor.
If your not comfortable with this the charging gas will always work. I usually put the cylinder somewhere inside the engine compartment to warm it up during charging.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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First things first ( whether you chose to do it or not )....

Since you have had a leak... your system is considered contaminated ( search to see great posts on this )...

So the first question is " Did you flush your system ? "