I converted my A/C from R12 to R134a for $40
 

I noticed my A/C had a small leak about 4 years ago. So every 1 to 2 years I have to bring to A/C service center for a re-charge. Since R12 is very expensive, every time I have to pay about $100 for the service, even though they only added about 16 oz of the freon. Some places would not even re-charge for you, because it is against law to fill R-12 in a known leaked A/C system.

So I decided to say good-bye to R12, bought R134a retrofit & charging kit for $39.95 from Pep Boys yesterday.

I just followed the instructions from the kit, and in 30 minutes my A/C system is running very cool with R134a. Since I know there is a small leak exist in my A/C system, all I have to do is every year or so add 1 can R134a ($6) and some oil charge (o-ring conditioner). I did not replace dryer/receiver or o-rings.

One more thing, before being able to charge the vehicle the R-12 needs to be removed. In the old days you could just depress the valve to let what is left of the R-12 out. It is like letting the air out of a tire. But that is against the law. You are supposed to have the R-12 vacuumed out (recovered). I would not tell you how I did mine. The choice is yours.


David

______________________
1985 300D Turbo

Did you evacuate and flush the compressor of the r12 oil ? If so , how did you determine how much oil to put back into the system ? If you did not replace the the Reciever/Dryer are you not worried about adverse effects of mixing the oils there? Greg

Greg, I just converted to 134A also in my 300SD. As I understand it, there are no immicsibility oil problems with the conversion if POE oil is used. Now PAG is another story and I would never convert a R12 car to 134A with the use of PAG. The conversion kits from Pep Boys use a can of POE with refrigerant for the conversion. I too would recommend a deep vacuum for some time to eliminate moisture and all R12 but my buddy has converted over 60 cars so far with nary an inch of Mercury vacuum on any of them! The POE will become the dominate lubricant and the old mineral oil will just sit in all the low spots like reciever dryer, condenser and so forth. Kinda funny: The R12/134A thread is getting to be just like the ole Synthetic vs. dino oil thread......

I did not evacuate and flush the compressor of the r12 oil. The instructions from the conversion kit did not call for that.
My friend converted his 300SD from R12 to R134a last year. He did not evacuate and flush the system, nor did he replaced any o-rings and the dryer/receiver. His A/C system still running good.

When you go to a shop asking for R12 to R134a conversion, they definitely tell you that: you need to evacuate and flush the whole system, you need to replace the o-rings, you need to replace the dryer/receiver. Otherwise they cannot justify to charge you a lot of $$$ for just put in one service pot , 3 cans of R134a and 1 can of POE oil.


David


_____________________
1985 300D Turbo

I did something similar on my old IH Scout. Worked like a charm! Unfortunately, the compressor was on it's way out anyways (bearings were out; sounded like a dying water pump), but for the year or so that I had it, it worked quite well. FWIW, I had a shop evacuate the system completely first, but I don't think they went so far as to flush it. And the R134a was quite cool; worked very well for this area and going up and down California on the I-5.

Just my $.02...I probably used the same kit, BTW. :cool:

I did mine 3 years back
 

Hello everybody:
I am new on this forum. I drive a MB 1985 300D Turbo, 123.
Mileage: 179,000.

I did mine using a similar kit purchased from K-mart for about 29.99( Interdynamics). It works well but I have to add a can or two every year. But Its still cheaper.
My advice, If you dont have a leak its good Idea to have a deep vacuum done to remove all old R-12 and air/moisture traces etc.
Then recharge with new R-134a kit. This I am told improves the life and eficiency.

Yes, you can indeed in most cases have cold air quick and easy with one of these kits. There is an old adage that comes to mind though, that is: "If it looks too good to be true, it probably is."

Evacuating the system is NOT merely a means for the shop to charge you more money. It IS a means of removing the dreaded moisture from the system. The moisture H2O(part hydrogen) mixes with chloride in the refrigerant to make an acid. This acid will eventually eat a hole from the inside out somewhere in your system. For a long term fix, you really need to evacuate the system prior to charging.

This also reminds me of a slogan of the old Fram oil filter commercial, that is: "pay me now, or pay me later."

Best of luck,

Over at aircondition.com they call those $29.99 packages "Death Kits." While thay may be a bit of hyperbole, it is definately better to flush out the mineral oil and vacuum the system. Excess oil lowers the performance of the system, air in the system stresses the compressor, and as Larry has pointed out, water is a long term death knell. The reason the shops are more expensive is because they are doing it right - they don't want you back in a year complaining.

Thank you Larry, I second that.

BOUGHT THE SAME TYPE OF KIT FOR 18.99, 1/2 OFF SALE AT MEIJERS. WAITING TILL THE FAN GETS FIXED FOR THE RECHARGE.

THERE IS A GREY COATING ON THE ENTRY TUBE SIDE OF MY FINS IT ALSO IS ON THE TUBE CONNECTIONS NEAR THE CONDERSER. WHAT IS THIS???

THE COMPRESSOR WAS UNPLUGGED WHEN PURCHASED. I HAVE PLUGGED IT IN BUT AM NOT SURE IF WORKING. I HAVENT SEEN IT ENGAGE. IS THERE A WAY TO "MANUALLY TURN IT ON AND OFF"??

THEY SAY A CHANCE OF SNOW THIS WEEKEND (5-18) BUT THE A/C SEASON IS COMING SOON.

You would not want to direct wire it without being sure your utilizing the high side switch and the low side switch in the circuit.... otherwise you would soon ruin it... and just might explode it like a bomb.

i would not like to see it go off like a bomb. so maybe i'll let a sleeping dog lye.

other posts have stated the compressor will run when defrost is on. so maybe i'll try and test it that way.

still like toknow what the greycoating is on the fins and pipe

:mad: As a professional mechanic the thing I would have to say is these kits should not be sold to the public for many different reasons. 1) I as a mechanic am not allowed to dump R12 into the atmosphere, there is a large expense involved with recovery equipment and EPA compliance 2) most do-it-yourself people will do this job on their own and not flush the a/c system and not put a vacuum on it before charging it and then bring it into a shop 6 months later when it doesn't work and complain because the bill to correct their errors is so high

GUYS, THIS IS THE WAY IT WORKS!! My shop rate is $40/hr, if you want to help then it goes to $60, if you played with it first, the rate will be unbearable because I now have to figure out what was done and how to correct it!

There are some things that tooling and experience are required for. Air conditioning is one of them so the job is done correctly.

I totally agree. My friend has a TV repair shop and I see first hand what happens when somone tries to "fix" something then comes to him for help. He has the same pricing structure ;)

300 D Grey, You may have to shoot a digital pic of that grey coating... for us to be able to guess/ascertain what it is... Greg

MtrDoctor12, You went from an absolute "not sold to the public" to " most " in item 2. I would like to defend some of the public.. like myself... who I think should be able to buy the kits but are not certified asme or own recovery machines...here are my reasons....
1. when I have a car which has freon it it I take it to a recovery station and have them check for leaks ,, and if any are found have them evacuate the system...
2. Most of my cars did not have any charge in the system when I got them...
3. When I work on them I flush every part. I had a gallon of Triflorochloroethane ( or close to that) in my refrigerator for 10 years (cost $40 a gallon).. this was 15 years ago... that was the legit flushing agent at the time.
4. I always put a new reciever/dryer on the unit if it has been open, or if a new compressor is being installed.... I understand how the silica jell can become messed up and how the little bag holding it can disintegrate...
5. I have a vacuum pump and understand that the system has to be cleaned of moisture.. and that is the only way to do that...
6. I use the oil recommended for the medium...
7. I read all I can about any procedure before I do it.....
8 . I have the proper gauges.....and use them properly....

9. I once built a great working air conditioner from parts laying around and installed it in a Karman Ghia.. it put out 28 degrees at the dash..( I have the same pro thermometer you have )(yes I cut a hole in the dash and installed it there... like factory if they had ever been available from the factory )... It had all the proper switches but my mind was fried by the time I got through.. electricity does that to me...

" the public " includes a wide range of abilities and attitudes... I don't think I should be penalized just because your generalized statements are true... Greg

I can see the reason why lots of mechanics do not like the ideas of the R134a retrofit kits around. Because they lost lots of potential customers--those owners of older cars using R12 refrigent.

The EPA regulations of R12 freon make owners of old cars pay outrageous prices for fixing their A/C system, or just annual re-charging. Then the retrofit kits came to our rescue.
Of course the mechanics lost lot of business because of that.

Actually you don't need to be a rocket scientist to understand the auto A/C system, especially the new R134a is very user friendly.

Following is the link to understand more about auto A/C system and do your retrofit:




http://members.tripod.com/~jbabs714/autoac.htm




David

___________________
1985 300D Turbo

That is a very good page but it has one small mistake... when purging the fill line you should attach it to the low side before running some freon into it... you just leave it loose,, and slowly let some freon into it to push out the air AS you tighten down the fitting... if you just flush it and then put it on then you have air in the hose...If you have gages you need to do this also being sure you know which way the valves work on them... also,,, wear goggles and full face shield when doing ac work... lots of potential for being hurt and or blind the rest of your life... Greg

This is some of the best info I have ever gotten on the site.My 80 has a slow freon leak.It cost a fortune to replace the freon.I am going to buy the pep boys kit and have some cool air.All of this enviro,crap is just that the leftest liberalswith a lame philosiphy looking for something to keep them alive.Remember acid rain.Thanks for the info.you leftest tree huggers can kiss my czarist postireor.Michael Rybikowsky.A name with a statement.

Michael,
Don't blame the tree huggers. They had nothing to do with it. Dupont's patent ran out and they told their congressmen, all of them, that it was time they started earning their donations. The rest of the world wants to go to a cheap and abbundant CO based refrigerent and many including Japan, Holland, and Germany have in stationary A/C units. They are still somewhat stuck with 134a in mobile air conditioning because of the industrial might of the US. If you want to find out what is going on in the world, you are not going to find out through local TV, radio, or the newspapers. The internet is a powerful tool to find out what is happening in the world, but unfortunately too many people use it for chatrooms, online banking, and downloading music. Remember, we do not live in a democracy as many FLAG wavers think. WE live under a two party system. I'm not degrading our folks in washington, they are all highly skilled. THEY ARE THE FINEST MONEY CAN BUY.

My observations which I can back up,
Peter

PS: This may be my last post before they bust in and take my computer.

I am enjoying this thread very much. There are so many controversial areas within the same thread, it makes for great entertainment.

I'll tackle the "evil mechanics" debate first. I really don't think that mtrdoctor is saying what he is saying about the death kits so that he can charge someone for his service. I fully expect that he has all the businees he needs, and will be billing his shop rate whether it is to rebuild an air conditioner that was destroyed by a death kit, or doing a valve job on the mayors car.

I believe that his point was, that once the system is ruined, and he has to do a bunch of work that could have been prevented by doing it right in the first place is very frustrating. I expect that it adds to his frustration when someone accuses him of being the bad guy, by the very one that ruined the system in the first place with the death kit.

The need to flush, evacuate and put in the correct oil is NOT merely some conspiracy by the shops to steal money from the innocent customers. There are very valid reasons for this being necessary. You can do it right the first time, or you can do the quick fix with a death kit, which will ultimately destroy the system costing MUCH, MUCH more money to do it right later. It's your choice.

The reason to take it to the shop if you don't have a vacuum pump, etc, is not to capture the R12 to satisfy the tree huggers, it is to see that the system is flushed and evacuated so that the job is done right. If you don't evacuate, there will be moisture left in the system which will combine with the refrigerant making an acid that will eventually eat a hole in something which will force you to take it to mtrdoctor so he can spend lots of time at his shop rate replacing some very expensive component. Of course, then you have mtrdoctor to blame for the expense.

As far as who is responsible for the lack of R12, I have heard these two arguments for some time. One argument is that Duponts patent ran out so they wanted to make something new to maintain their profit. The other argument is that the tree huggers demanded something more environmentally friendly.

I side with Michael on this one. If all the R12 in the world were released from all the air conditioners in the world, it would not match the atmospheric damage of one volcano blowing its top.

The choice you choose to blame for the loss of R12 from the store shelves is most likely connected to your political beliefs. All I have to say about this is that I believe that the entire congress should have had to spend July and August in a hot, damp climate before voting on the R12 death bill.

It's always amazed me that once someone is elected to congress they are INSTANTLY an expert on every subject known to mankind.

There is no one more frustrated about R12 than myself. I have about six pounds left and I don't know what I'll do when it's gone. Every summer, I cross my fingers and turn on my 124 air conditioner. So far it still works well. When it doesn't that will be the end of my R12 and may wind up being the end of my otherwise wonderful stick shift 300E.

Now that I think of it, the 300E is the only thing left on my place that uses R12. Of course, my old farm truck has no working a/c because the r134 doesn't agree with the Tecumseh compressor. Maybe next year I'll do something about that one.

My $0.02,

There is an interesting article at www.import-car.com regarding many of the issues in this thread. Go to the site and check the article "A/C Update."

Vince,
Good article, although I noticed it was carefully written to not step on any toes. I was glad to see the article referred to the rest of the world going to a CO based refrigerent. Most of the supermarkets in Europe are already being converted to this cheap, natural, and abundant refrigerent. As an aside, anyone who has flown on a French Airline or traveled the backroads of places like Belgium, France, or Germany still won't be able to find any ice cubes.

So I've read all this stuff and don't disagree with those who argue "do it right" but I am somewhat surprised that stores like PepBoys will sell a product that, according to several very experienced people, can cause serious problems for the user.

But.....I think I'll just wait until my R12 system fails and then go see my trusted independent shop.

And for those of you who view our government with suspicion and distrust, bear in mind the alternatives. Most of us would agree that we need some sort of social system. A benevolent dictator would be great, but you know how that goes (he or she dies and we get stuck with his or her malevolent offspring).

I have worked in a state legislature for some time and have come to believe (took a while) that the crazy thing generally works pretty well. Not always, but usually. There are plenty of self-interest groups (and not all represent the ruling class) and some lame elected officials but you would be amazed at the number of "controls" inherrent to the system. Legislators watching, public agencies watching, staff watching, lobbyists watching, citizens watching, and the press watching. Bad stuff gets through and the big boys get their share but all in all, I'm pleased to report that it really does work.

I am conservative, obstinately independent, live out in the country, and hate to be told what to do so believe me when I say that you can take some comfort in what we have. Don't sell it short.

Nic

OF COURSE the "threat" of R12 being the death of us all is bulls**t! Just like how we're told the EPA must save us all from the "threat" of diesel exhaust!

It's ALL political.

There's SO much paranoia in recent years about global warming...

In the 60s, many "scientists" were in a frenzy about GLOBAL COOLING!!!

So which is it?!?!?! What looming global catastrophy do we need to worry about next?

Gotta' keep the paranoia going, so they can keep the taxpayer-funded government research grants rollin' in!!!!!!!!

YOUR tax $$$$$$$$$$$$$$$$$$$$$$ fund this crap! GO VOTE!

Venting, again.... ;)
Mike

NIC,

It was amazing how well your last sentence describes me.

I agree with much of what you said in that post. What I really believe is that there is NO politician today at ANY level that can take credit for ANYTHING going well in the US. The credit goes to the founding fathers for setting up a system that has the checks and balances that you talked about.

I hope that we continue to be smart enough to prevent ANYONE from changing our constitution. The democrats, in their platform, call for a Constitutional Convention. This would basically be rewriting the constitution. This is the most scary thing that I can imagine ever happening to the good ol' USA. To me this is scarier than all the suicide bombers that you can find.

My $0.02,

Amen Larry!

Mike
:)

Mike,

It sounds like you are a thinking man, and this thread has redirected from a thread about air conditioning to politics. I can only add to your comment about every one going out to vote. If your'e going to vote, take the many hours required to go over the ballot issues and review the candidates running for office. What can be more importent in our lives than taking a few hours to determine the quality of our lives. One important reason voting lines are sometimes long is because, many voters wait until they are in the voters box to look at the ballot. Then they must recall who they last saw on tv that sounded good. It's the big money that can afford the advertising that gets the vote. As to changing the constition, I say why not if it needs to be done. It has already been done many times in the past; that's why the're called amendments. Has anyone ever heard of the 1st amendment, or the 2nd amendement, etc. We Americans think we are so great when many other countries think we are barbarions. Don't get me wrong; I'm happy to be an American, but I think we need to do some soul searching. As an example: we bombed the crap out of the Taliban, but how many innocent people suffered because of it. Not many Americans know why the Taliban was in power. The US government helped them to power, because there were too many random forces, and UNICAL wanted to put a pipeline through the country. It's all documented. Check it out. We've spent billions of tax payer dollars to destroy the country, and now we will spend billions rebuilding it. Mike, I'm venting also. Nic, I agree that America is still a great country, and it could be even better if the citizenry would wake up. What other country would I be comfortable in? Try Singapore. Think that one through. My thoughts.

Thanks,
Peter

Some good points, Peter.

However, amendments do not CHANGE the Constitution, they just ADD to it. The core of the Constitution has never been changed, and should not ever be. It is very often IGNORED nowadays :( , but not changed.

I doubt if many of those who think Westerners are barbarians have ever been here, or anywhere outside their own country. Or VILLAGE, for that matter.

Hiding in caves or blowing oneself to bits for some "righteous" cause seems to pretty much fit the definition of "barbaric" to me....

No country, or person, is without fault.

I apologize for helping to steer this thread away from the original question...I tend to get on a roll sometimes...OK, often! :D

Mike

I also apologize for pushing things even further toward politics in this thread, however, mikemover I'm still in tune with you.

I'm also very intrigued about how someone can make all these judgements about our country without ever having been here. It's also intriguing to me when I see how many things are blamed on the evil oil companies.

Also, that big money that is spent on political campaigns, like it or not, is one of the things that makes up the democratic process. To limit money spent on political campaigns, is to limit the democratic process. For most people, what determines whether or not money spent on campaigns is fair or not, is determined by whether their favorite candidate in that particualar campaign is getting more money or less. IMHO, neither party has the right to pass any laws limiting campaign contributions of any kind. In the past the money edge has gone to both parties at different times. The fact that a particular candidate is getting more money spent on them should tell you something.

God Bless America,

I too think this thread should ease closer to the ac subject but I want to agree with the statement that Autozen made about voting....

" If your'e going to vote, take the many hours required to go over the ballot issues and review the candidates running for office."

All the time I see the media telling people to go out and vote, lamenting over questions being decided on very small turnouts, etc... I never hear them say what Autozen just mentioned... Many people have turned Democracy into a religion in their heads instead of a rational process.... They think that the "number" of voters being large will make an election 'good' or 'right' and it takes something different than just bodies pulling levers... Lots of informed bodies pulling levers is good. The USSR used to have right at 100% turn out in elections ... now that I have had my turn, back to the ac questions... LOL... :) Greg

Mike,

I was referring to other leading countries views of the US. You are right though; this thread is getting way out there. We should end it unless someone has a comment on air conditioning. I've enjoyed the dialogue. I can tell my views are pretty left compared to the rest of the group. I've spent half my life living two towns away from Berkeley, Ca. That may have some bearing.

See ya,
Peter

I also agree with autozen that if you are going to vote just so you can truthfully say that you voted, you are probably not going to contribute very much. The key is to do your research and let your vote represent the effort that it deserves, regardless of your political leanings.

To comply with the request to move the thread back to air conditioning, the a/c on my 300E is still working quite well.:D

Have a great day,

PS: One of the most conservative guys that I ever knew was a good friend of mine when I was in the Army. He grew up in Berkley, and in spite of the turbulence of the time (1969 - 1971) he was quite the conservative. Just because an area has a reputation for leaning one way or the other politically, does not mean that EVERYONE in that area represents the pervasive thinking of the area. LB.

I think the University there is a lot more to blame for the reputation than the town itself.

So many damn college professors think that becuase they excel in one particular field, they have the whole world figured out. I had a few heated debates with out-of-touch faculty when I was in college. :) They are so quick to look down their noses at the "capitalist society'" point of view...How easily they forget that the "capitalist society'" tax $$$$ keeps them EMPLOYED!

Obligatory AC content: My damn AC still does not work. :mad:

Mike

mikemover,

Yes, many of the professors most definitely do NOT live in the real world. Some of them need a few years in industry EARNING a living, then they would be better prepared to give our kids a jump start on the world.

Some of them, however, figure out how important it is to encourage their students to analyze and think on their own, rather than merely believe whatever a professor or anyone else tells them that they should believe.


The manifold on the R4 compressor in my daughters 300D is leaking. I hope to fix it this weekend.:D


Have a great day,

Help with a few Q's
 

I am reading this thread with great interest because I am about to perform this with the death kit on my 1987 300TD. The AC system has a leak and it has not worked for the last couple years. I do not care if the death kit messes up the system or not as this is the final try to get some cool air. If it fails, then this car will not have cool air for the rest of its life.

So I went to K-Mart and bought the kit. Three 15 oz cans with refringent and ester oil pre-mixed (12 oz and 3 oz). Before I do it, I have a couple questions and appreciate answers from those who have done it.

1. How long does it take, on average, for a can of refringent to go into the system?

2. Once the quick connecter is connected, do I still have to push on it during the charge phase?

3. Once the system has enough pressure, the compressor (if it works) should kick in by itself, right? I seemed to remember reading somewhere that a wire has to be jumped to get it going.

loubapache,

I know nothing about the connector on the death kit and how it works, but maybe I can offer a little help on the other two questions although not in order.

You will not need to jump anything when charging, once there is enough refrigerant in the system, the pressure will increase to the point that will actuate the pressure switch and turn on the compressor.

The first can will go in very fast, maybe a minute or two. Each successive can will take a little longer due to a decreasing pressure differential.

I would still urge you to find a friend with a vacuum pump, and pump down the system before charging, but regardless of your method, I wish you the best of luck.

Have a great day,

Thanks, Larry.

Going out to try now and will report back.

Well, I am back and I failed the first time. It was taking way too long for the first can of refrigent to go in so I shaked the can. Then the supplied charging hose came loose in a little connecter and some refrigent escaped from the can. I managed to push the hose back in but the refrigent was still going in very slowly. I then tried the second can and it was also very slow. So basically the kit is ruined (the hose) and it is hard to know how much refrigent I got into the system. The system does have some pressure now because once I connected the hose I can hear some refrigent escaping. The compressor does not come on.

I may wait a few days and then get another charging hose and try again.

Bo,

Did you bleed the system first?

Good luck,

Mike,

You never stated the symptoms of your a/c. Are you out of gas or what? That ACC system in your 300SD was a piece of garbage that MB bought from Chrysler in the early days in an effort to attract the attention of the buyers of luxury American cars. MB also bought a cruise control system from Ford that never really worked well. At any rate I just repaired the ACC on a 1980 300SD I own. The heater stayed on, and there was no a/c. I moved the temp dial(same system you have) from limit to limit and listened under the hood for the servo to drive. It didn't. You can do voltage checks, but I cheated and plugged the 2 electrical plugs into another servo. The servo drove limit to limit, so
I installed it.I now had heat control but no a/c. I hooked up my charging station and sucked it down to a vacuum for 45 minutes. It held the vacuum indicating no major leak. I put in a kilo of r-12. I too have been trying to figure which way to go. R-134 just doesn't work as well as R-12 and probably will only be around a few more years if the rest of the world has its way. I'm still looking at the feasability of drop ins also. For now I'm sticking with R-12 because I think market forces will bring the price down. There is plenty of R-12 available and as soon as the suppliers see that the amount of R-12 cars is dwindling, they will be forced to compete in the market place. At least that is the economic model should work under laisez-faire economics. If the public sector (government) enters the market things could be different. Assuming R-12 is harmful to the atmosphere this whole madness could have been avoided by making it available by license to professionals ONLY to be handled under strict regulation. The same story goes for asbestos removal. The government spent millions of tax dollars removing it from schools and public buildings. The stuff isn't much of a hazard until it becomes friable, which is what happens when you remove it. When I bought my house I questioned the material in the textured ceiling, so I took a sample to a friend at a lab in Berkeley. Sure enough the sample contained Crisatile(sp) asbestos. After doing more research I was advised that the practical approach was to paint it again and seal it in.Maybe in years to come, more research grants will determine asbestos is safe again or they will have developed a shot for asbestosis. At any rate back to a/c.

Peter

<<
Bo,

Did you bleed the system first?
>>

Good question, Larry.

My inexperience in AC system really showed today. The previous owner told me that the system has a slow leak. There was one service sheet saying that the system should be checked for leaks. So I took that for granted and was thinking the system was empty al the way. Thinking back, that might have not been the case.

No, I did not bleed the system.

Now it looks like either the compressor or the pressure switch is the problem. Or it could be something else like the push button controller.

The system has plenty of pressure now.

Well, I think this car will have no cold air for the rest of its life.

Bo

Go to any auto parts store buy yourself an auto a/c R134a pressure gauge(about $20). With engine on and air conditioner turn on to maximun cool, measure the low side service port . The gauge should read 35 to 45 psi @ 75 degree F ambient temp.
(25-35 psi @ 65 degree F ambient temp) You do not want to over charge the system.

I started this thread about 2 weeks ago after I converted my a/c to R134a with this "death" kit. It still working fine like a charm.
May be this is the "resurrection" kit to me.


David

__________________
1985 300D

Bo,

There is an additional issue here. When you DON'T draw a vacuum, there is air at atmospheric pressure, or thereabouts, in the system. This air being present makes less room for the refrigerant.

If you had a friend with a vacuum pump and manifold guages, it would probably be relatively easy to troubleshoot the system and find the problem.

Actually if there is pressure at some level in the system, that is a good indication. The biggest problem is usually that there is a nasty, expensive to repair leak somewhere. If it has pressure then there is probably not a serious leak.

I don't know where on your particular model you would find the low pressure switch so that you could jump it and see if the compressor will kick in. Also have you checked your fuses?

I wish I were nearer to you so I could offer a little more help.

Best of luck,

David:

Yes, I will get the gauge just to make sure the problem is not refrigent pressure related.

If the pressure measures OK, then I will look into the pressure switch.

<<
I don't know where on your particular model you would find the low pressure switch so that you could jump it and see if the compressor will kick in.
>>
It looks like the switch is near the sight glass. I cleaned the contacts first (but have not started the engine yet). I will wait for a week to see if the system holds pressure. One thing at a time, I guess.

<<
Also have you checked your fuses?
>>
Will do that too.

<<
I wish I were nearer to you so I could offer a little more help.
>>
I really appreciate this, Larry.

The compressor works but no cold air
 

Well, the compressor works. I jumped the switch and the clutch engages. I then put the wire leads back on the switch and the clutch also engages. There is about a 10 second delay between starting the car and engaging the compressor switch.

So the compressor works. That means the system has enough refringent pressure, all fuses and relays are OK, and the push button penal works as well, right? But it does not blow cold air. The search for a solution continues.

Bo,

Can you find a sight glass? I have never had to do anything with the air conditioner on my 124 car, so I don't even know where it is. I would look behind both headlights looking for it. If it has a sight glass, you will need to charge until the glass shows clear with no bubbles moving through it.

If you can't add enough refrigerant to clear the glass, you need to find a buddy with guages.

I think you're in better shape than you think. I still wish you would blow that charge, draw a vacuum then charge it. You apparently have all the necessary ingredients, a running compressor, r134 fittings, and apparently no significant leaks.

The 10 second delay after engine start is by design. It is so that the engine has plenty of time to build oil pressure before loading it.

There is another very real reason for drawing a vacuum. It serves to remove moisture from the system. Any moisture left in the system combines with elements in the refrigerant and produces an acid that will eat a hole through system components from the inside out. This phenomenon is much worse with r134 than with r12.

Given a vacuum pump, manifold guages and a canister of r134 or can tap with individual cans of 134, would not be a big deal to evacuate and charge. It would also give you an opportunity to put the correct oil in the system. The mineral oil used with the r12 will not correctly combine and circulate with the r134 which, of course, results in inadequate compressor lubrication.

If that car was in my shop, it would only take some ester oil, about 3 cans of r134 and about an hour for me to have it evacuated and charged, although I would prefer to evacuate it overnight to remove as much moisture from the system as possible.

Sorry for the sermon. As you can tell, by necessity, we probably have more experience with air conditioning in Texas than does the average Joe in Michigan. Of course, I'm sure that heating systems are a little different situation.

Good luck,

Thanks, Larry.

I think I will wait for a week to see if the pressure holds. If it does, then I am thinking about taking it to a shop to have it done your way, i.e., evacuate it and charge it with R134a.

In the interim, I wil get a gauge to see if the pressure is up to specs.

Thanks again.

OK,,,,, lots of people have spare ac compressors laying around ( everyone is a packrat , right? ).
They can not be used to make air compressors because the method of lubrication is by the flow of oil mixed with coolant....
How would one make a vacuum pump which could be run with an electric motor and could be left on over night to use for evacuating ac systems...
There must be some way to do this... I have about 6 good compressors... both types... could I place a reciever dryer with oil in it upstream of it? Do I need to tap the head and provide some metering device for small amounts of oil to be injected ? Could I use one of the turbo oil jets to spray the bore from the underside ?
I know this can be done, so no "it can't be done"s please,,,, It is just a machine and physics...I have seen old style ones which were good for long evacuations... they just dripped the water out of a hole...
And lets get those answers posted quickly as I am about to start on my new 240d's ac..LOL...:)
Thanks, Greg

Larry and David:

Thanks for your help.

For the time being, I am giving up on the AC.

I got a pressure gauge and there is plenty of refringent pressure (too much, as a matter of fact so I had to bled off a bit).

Now I am not so sure if the compressor kicks in as I tested in the ECON mode and it does the same thing.

The previous owner did honestly tell me that the AC was the last item that made her to sell the car. So I think there is something (big) wrong in the system.

Just have to live without AC on this car in Michigan. Luckily I have two others MBs that do have working ACs.