I removed those tubes at the expansion valve in my 1985 300D a few months ago, using regular wrenches (big open-ended HF & thin adjustable wrench). I removed the expansion valve too. The task was to replace the bigger suction hose since it was leaking thru the rubber, but I changed all O-rings at the same time. I have a recent thread on how I replaced the hoses. I didn't replace the small "liquid" tubes since they looked fine and rarely fail.

I am about to do the same on my 1984 300D. I started on the broken oil pump tensioner, but those hoses were in my way and looked ready to fail, so figured "why not now" and also eliminate that cumbersome tube run behind the alternator.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I've made an appointment for next week to get the R12 evacuated from my system so that I can get started on this project. I found this good tutorial for replacing the W126 expansion valve: Removal and Replacement of Expansion Valve

One of the final steps is to lubricate the o-rings with the same oil used in the compressor and drier. Which oil should I use? All of the PAG oil that I've seen on line is for r134. I need something that comes in a bottle. I'll be replacing the drier too, how much oil goes in there? Thanks

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'81 300SD

Now that I've had my AC system evacuated, I'm ready to start replacing parts. I've ordered an o-ring kit and plan on replacing as many of those as possible. Once I have everything installed I plan on adding 2 oz. of PAO68 to the drier and 5 oz. of PAO68 to the compressor. I've been told that I should rotate the compressor by hand after adding the oil to prevent hydro-lock. How can I engage the clutch on the compressor in order to do this effectively?

Once I've oiled up the compressor, can I start the car and add R12 through the low side port like I normally would when charging the AC, or should I take it to a shop? Thanks

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'81 300SD

Just turn the center of the clutch by hand. If you did power up the clutch, it would be engaged against the drive belt and you would not be able to turn it.

Okay, I thought that you would loosen the belt, engage the clutch and then spin the pulley by hand. I don't know much about AC systems. Is the clutch suspended in the center of the pulley when not activated, and then magnetically attached to the pulley when engaged?

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'81 300SD

If the system gets all o rings changed, then oil installed, then pressurized with a dry gas and leak tested. Then it needs to be totally evacuated, and liquid weighed in, the high side, then vapor topped off until proper subcooled liquid is in the receiver.

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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 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Bummer. I was hoping that I could just use the three 14oz. cans of R12 that I have. I know of a garage that still has R12, but it's $70 a pound. Would you guess that they'll use 2 pounds of their R12, then top off with whatever they can use of mine?

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'81 300SD

Yes, the face of the clutch is pulled towards the pulley making contact and driving the compressor.

As for recharge, the R12 cans don't seal very well once punctured so I'd tend to use full cans only then have it topped off at the shop. R132 cans have a screw on top making them less leak prone.

I was planning on emptying all three of my cans of R12 into the system, but according to vstech, the system needs to get started with weighed liquid R12 first.

I also just saw that my Egelhof expansion valve has R 134a printed on it. I'm hoping that this means the valve is compatible with R134a, but not solely for use with it.

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'81 300SD

Systems are never charged through the high side when running. Charging through the low side with vapor while running is typical.

A heated charging station is really needed if pumping liquid through a non running high side. Even then that is more for large scale charging / at the factory charging.

What is the capacity of your AC system? What you do is divide can contents into AC capacity. If part of a can is needed, weigh the can / valve / hose as hooked to the car, watch the weight change then shut off the can when done.

The R12 capacity for my car is 3.3 lbs.(52.8 oz.) . I have 42 ounces of R12 in cans, so I was just going to empty all of them into the low side port and top off at the shop if the vent temp wasn't satisfactory.

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'81 300SD

I got started on the job last night, and threading the bottom two fittings back into the expansion valve is a nightmare! I threaded the top two fittings in no problem and left them very loose so that I would have enough play to get the bottom ones started. Since that didn't work, I torqued up the top fittings thinking that raising the valve up might help line up the bottom, no luck.I then checked the engine bay to see of I could create a little more slack in the bottom hoses by disconnecting them an pushing them towards the firewall. The plastic sound buffer prevents either of those lines from moving back to give me the slack that I need. Any tips from guys who have done this before? Thanks

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'81 300SD

OK got it, I was thinking the system took less than that. I'd still have the shop pressure test before you recharge in case there is a major leak. You will need them to vacuum the system before you recharge anyway.

Not an AC expert, but it you are keeping the system R-12, this doesn't sound right to me. Two different gasses with different pressure curves, I doubt a TX valve is made that is designed for both. However, the MB factory guide for replacing R-12 with R-134 does not require replacing the TX valve, so go figure.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Oil: what weight of oil does your compressor need? When I started doing AC work on my cars, I had no idea there were different weights of oil required by different compressors. My 124 cars need a light weight oil (40? from foggy memory), most of the oil on the shelf at FLAPS is 100.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC