Thank you Larry for your other response..... Now folks my compressor is shot and I want to replace those parts that are most likely to fail. I do not want to be a penny thrift and a dollar foolish. I am concerned with the do's and don'ts when working with this system! The system has been depressurized, when connecting new parts to the system do I coat the fittings with refrigerant oil ? Should the drier be the last element of the system to be connected? And should the system be flushed before recharging it with R134 ?

Don't waste your time puting that trash in your big $$$ AC system. Get the real R12, you won't regret it.

BTW, I got a quote of $30/lb for R134a and $70/lb for R12 plus $80 service.

82-300td... I am in Los Angeles and have no choice in the matter(R134). I like your futurama quote. Any other views on do's and don'ts?

Do's:

Flush
Flush again,
Flush some more
Reverse flush,
Finish up with a flush,
Get all flushing agent out of system.
Coat o-rings with Nylog, if that's not available coat with refr oil
Put in the correct amount of refr oil
Connect up your filter drier last thing before evacuation
Evacuate thoroughly
Make sure you have the correct seals for the R4, there are different ones
Use mineral oil and R12

Don'ts:

Don't even think about a new compressor without thoroughly flushing
Don't use anything but R12 and mineral oil

Good luck,

Thanks Larry....I have seen the LIGHT ! No R134 ! I am going to get a flush gun and go to town ! Any problems with the fact that my system was retrofitted with R134 fittings? Can I get by with my old condensor( seems to be OK) ? I will not be evacuating and charging the system myself. I will have to drive the car about 8 miles to the A/C shop and have it done. The compressor oil filling when and how?

Less than 24 hours from ' I am in Los Angeles and have no choice in the matter(R134). " to
" I see the light' ..
What happened ?

You can take off the 134 fittings... in fact the law would require that even if you could use them to install the R-12...

Remember that your Txvalve ( Thermostatic valve) must match the refrigerant ..... so if they had a R134 in it you will need a new R12 one....

If you flush well... you can use your condensor... however, you need to take it off your car to do this ...

The most important physical factor ( Bottleneck ) affecting air conditioning performance is the AIR ACROSS THE CONDENSOR.
Therefore buy the best aux fan you can afford. That with the R-12 and normal condition of the rest of your system and you will be in good shape.

The real bottleneck in the ac system is the small evaporator they put in these cars. That said, I agree that among the things you have control over, getting air across the evaporator is most critical. that is why when i rebuilt mine (converted to 134) I re-wired the aux fan to go on with the compressor does...I do realize that there are times when I am tooling down the highway going 80 when the aux fan comes on with the compressor, and does essentially nothing. that is a trade off I am willing to make.

I did make a few other modifications to the system.....I put in a generic "parrallel flow condensor" to even further enhance the condensing function...to get low side pressures as low as possible. The system works well....center vent temps of 37-38 deg when outdoor temp. is 95 to a hundred (dry humidity). When its very humid though, center vent temps go up.

I dont quite understand why R12 is so much better than R134....after my conversion to R134, the system worked fine. The system cuts out when the thermal switch near at the expansion valve cuts out....this tells me that refrigerant temperatures are getting to the requisite temperature (somewhere just above freezing). the system would cut out at this temp. whether you have R12 or R134. What I find the main problem is, as I said earlier, the small size of the evaporator......it is just not big enough to cool and remove moisture from large volumes of humid air.

Mark

__________________
1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

I am just speaking physics wise... a system can be very puny if you had a GIANT fan pushing air across the condensor and still get cold air out of it...

Hey leathermang...The turn arround on R12 vs R134 game because of bad info. on R134 and solid background info. on R12.
After all was said and done the best thing for my " agavengrun" is what it was designed to take. I thank you all for the great help and I am definitely on the road to having a very sweet car.

From my other postings (seems like a lot on A/C systems today) I would replace all the systems hoses as long as you have the system apart. Also I would change over to R134a. You do have to have a rotary compressor but your '80 240D should have that. Ther are other things that need to be done and flushing the system is the MAIN one (not cheap).

Just my opinion on this from "rebuilding" the climate control in a '79 300D and converting it to R134a in the process. (total cost was over $1000)

__________________
current Benz
'87 300TD (white) 168K (on the odometer as of 15 April 2004)
past Benz owned & miles I put on them
'62 190D 20K (white)
'63 190D 20K (beige)
'65 190D 35K (white)
'73 220D 175K (metalic green)
'79 300D 135K (metalic blue)

driving a Benz diesel since'77

And what percentage of this cost was the refrigerant? For $15 you can take the open book test at www.imaca.org and get your certification to buy R12 in about 30 minutes. And I bought genuine R12 last year for $20 a can at Advance/Discount Auto Parts. It seems penny wise and pound foolish to spend $1000 to rebuild a system and then use the wrong refrigerant to save $50.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

Well MOST of the $1000 was to sort out the gawd-awful vacuum lines that the previous owner let get dissolved by the battery acid!
(ever seen where the climate control vacuum lines run in a '79 300D?)

Next in cost was the compressor/dryer/expansion valve/hoses.

Finally there was the system flush and the R134a recharge.

The thinking from my mechanic was that if you need it recharged R134a will run about $80 including labor (system leakdown/hold vacuum for 30 minutes/recharge with refridgerant) but the R12 will cost $200 for the same thing.

Thats it!

(I wish I had found this board years ago as I'm now into doin' more myself)

__________________
current Benz
'87 300TD (white) 168K (on the odometer as of 15 April 2004)
past Benz owned & miles I put on them
'62 190D 20K (white)
'63 190D 20K (beige)
'65 190D 35K (white)
'73 220D 175K (metalic green)
'79 300D 135K (metalic blue)

driving a Benz diesel since'77

CWA is new here and did not have a chance to experience the " Refrigerant Wars"..... but in addition to that life is just much easier once one realizes that Rick is always correct.

Only because I've spent 5 years studying the writing of people like Benzmac, M.B.DOC, steveblf, LarryBible, and of course, leathermang.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References