Hello
I have a 300 cd 85 and my ac does not work.
I folow some advice from this forum but i need some answers:
I check the low presure switch 2 wires one side -- check-- with signal ,one terminal does not have signal, i conect them toghether and my compresor start that mean my low presure swice has to be change? do i have to recuperate the r12 before that( logic yes)?that means i do have chances to have some r12 left in the system and how i can veryfie that at this time before recuperating?
thanks

First check that you have enouph refrigerant in the system. The low pressure switch might be doing its job. To reclaim to refrigerant you should use a refrigerant reclaimer. this will remove all of the R-12. Then you can replace your switch if needed and you can put the reclaimed R-12 back in or convert to 134A

First thank you for your answer
My problem is I do not whant to go to the shop before i now wath is the problem -how i will ceck the quantity of r12 with out compresor working and guages ,i do not have enough experience with AC.
I understand i supose to have juice at the both conections terminals at the lower presure swich and like i said when i shorted them the compresor worked
thanks again

Greasy is correct... and I am going to take a chance on hurting your feelings by telling you that you do not have enough information to safely work on your Air Conditioner...
I did several things when I started out.. this is one of those situations where a Little knowledge can really get a person hurt...
I am lucky a can of refrigerant did not explode in my face when I hooked up to the wrong side of the system.... I was about 22 years old.... but did know that the refrigerant can should not be getting hot ... so I quickly disconnected.... but it was very hot and I just got lucky..
Would rather have your feelings hurt than your body...Find someone with some experience with this stuff for your safety....

Please heed leathermangs warning. You will at the very least need someone with gauges.

Most likely the system is simply low on refrigerant. You need to take it to a shop where they know what's going on. Most auto a/c shops are not that familiar with MB's. They may want you to convert, but you need to know that these cars do not convert well.

Your best bet will be to check for leaks, repair if you find one and recharge with R12.

Good luck,

THANK YOU VERRY MUCH guys specialy if it comes from both of you which i now are the best in this chapter but i do not whant to operate myself on this system (charging or repairing) i whant to now what it is posible wrong whit it before i handle myself to the wolfs here in NY
I will like to be near to the place where you guys live to give you the car and sleep good nowing the best people takin care of it
I realy apreciate your concern for a fellow diesel owner whit out knoing the person , this show good caracter
thank you again

The problem is that Air Conditioning is very critical on things which you don't have the equipment to check...
Pressures, amounts, temperatures at certain places, etc....
I do not blame you for not wanting to hand your car and money over to the wolves...
But there are certain MINIMUM tools which you would need , in addition to a lot of studying the safety rules, before you can check your system....
Now, if you want to invest in the guages, etc... and get your 609 license ($15 open book test on the net ).... we will be happy to try to advise you on doing everything as cheaply and as properly as possible.... and those tools and knowledge will come in handy the rest of your life.... Even if you decide later not to do your own AC work.......Knowing if the wolves are telling you the truth is a major victory .
Think about all your options... one is to find an AC shop recommended by someone on this forum..... that might really help your feelings about the situation...
But to assume because it is not turning on the compressor that it is the SWITCH... is not the first thing to check... If it is DOING ITS JOB CORRECTLY and YOU BYPASS IT... you take a big chance on TRASHING your compressor.....and costing you Much more than proper diagnosing techniques will cost....

Thank you leathermang , LarryBible, and Greasy for you help
I did bought a book on AC and reading as much is posible in 1 day i realise how complicated and dangerous this bussines is so i whent to the first shop specializat in r12( not everybody has r12 in NY) where i find a guy which had the time to answer to my questions before i came whit the car. This guy ,german in origine i find out he is a mercedes nut like me, he has 3 mercedes in the back of his house various years 1972.1983 1987 gas al but the 1972 is coupe like mine 220 i believe in extremly good condition which himselv restaur.
Knowing all this, i brought the car and he did clean suck oil and charge my system for $125 which i believe it is not to much for this job.
At the end i help him to repair the braking system to the 72 we become kind of friendsand i did refer him to this beutifull forum.
A bout the license i will think over , it sounds tempting
For the rest of the forum people which live in ny i can refer you to this guy in case of need

That is great news,, and a good price ... particularly for your safety .
There is a place to tell others about a good shop when a person finds it...Here it is.....

http://www.peachparts.com/shopforum/good-mb-shops/?daysprune=

Sounds like my kinda friend.

I ended up purchasing all kinds of equipment including an r12/134 recovery machine and plan on learning how to service a/c system. I don't get the warm, fuzzy feeling that the local a/c service shops are as conscientious in regards to my cars as I am.

__________________
Jim

I am glad you got the Job done right!
I have been repairing A/C and refrigeration for about 18 years and a good auto a/c repair man or refrigeration repair man for that matter are few and far bettween..

This guy it is verry minutios whit his job and being a german 2 nd descendant it helps
You guys shoul see his 1972 car in what kind of condition , i whoud sleep in it if woold be mine
The thing which triger me it was the fact he enjoi to givme all the answers to my questions before i decidet to bring the car to him, he was proud for his work and i forgat to telyou guys he givme waranty for 6 monts after he diagnose my carwhich i do not heard of for AC until now
again i will like to thank to everybody for your help