I had to play with it. My mechanic put 28OZ of R134 as a retrofit, 1984 300d. he said that was 80%. I am pretty sure that the the R12 capacity is 1.2 Kg which is 43 0z which 85% of that is 36 oz. so i wanted to put more r134 in to make it run cooler. I read the instructions and added about another 10oz, Duh. the next day it kicks off while running due to high pressure i assume.
I dont want to go back to mechanic and look like a fool. Can I empty the system and put in three cans 36oz and feel good about myself (enviromental reasons). If I can do i release the coolant from the low end or the high end or both. and what do i do about the 8oz of oil he put in there. do i need to replace that or does it remain in the system.

Or should i just go back to the mechanic
(I only paid a mechanic three times in my life, I dont like it)

Thanks for your help and have pitty on a beaten soldier of auto maintenance

bob

PS even my wife is mad at me and she is very understanding

Unless you have AC gauges to monitor the actual pressure during charging or discharging you should take it back to the mechanic. If you feel uncomfortable go to another AC shop and have them take out some freon.

Vinamg

The bob screwed up.Find a quality ac person and have them put it right.My heart bleeds for you having to spend some money

Thank you for your replies

Mike, It is not that i am cheap. I just cant seem to leave things alone. The times i brought my cars to mechanics in the past was to repair my mistakes or complete my work. Im not the best shade tree mechanic but over the years I learned a few things and that is the fun part.

Anyway, I probably need therapy on this... and at times when I break perfectly good machinery I am reminded of my problem, not obeying the simple rule. "If it isn't broke Don't fix it."

I give up

I'll take it in.

Thanks for the help and great support on all my projects

bob

Bob you sound just like me when I was a lot younger.I just had to mess with things.It did not matter if they were working alright or not.I paid a lot of money over those years to pay people to get me out of the messes I had created.Like the mule and the two by four.It finally dawned on me to only work on what really needed work,and that I thought I could handle.All the best to you.Michael.Carpe Diem.

I feel your pain too...

I went to the dealership a year ago and purchased brake pads and sensors for my 300E. Wanted to save a little money, since I've done that work on some non-MB models I've owned in the past.

Tackled the rear brakes (no manual or CD or anything), over-dissasembled everything (calipers completely off, brake hoses off, etc.). Couldn't figure out how to get the front ones off. Had air in the lines (DUH) etc.

Sheepishly took the car to the dealership and handed them the remaining parts to complete the job correctly. Probably cost more than if I had them do it originally, since they had to bleed the system also.

These were my pre-forum days. Recently got my hands on a manual, and could kick myself, as the brake pad procedure was far easier than I went about it.

I have had other "Homer Simpson" shade-tree mechanic episodes, but this would be a long thread if I elaborated on them...but I have gotten extremely good at working on my Beetle, simply because I screwed up so much! I expect to be fairly adept at my 300E as well...

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Brother of The Benz, The Bob
What you want to do is normal for we DIY owners.
What you must do to get your A/C back to working is so simple that you will amaze yourself.
To purge the R-134A to the atmosphere is no crime against nature.
Go to your favorite auto parts house and purchase a charging hose/can-tapper/low pressure side. In addition buy a low side pressure gauge compatable with the other hose or a complete gauge set.
You won't spend over $30.00 for all.
Three cans of R-134A and a "Hot Shot" oil charge with stop leak and a dye leak indicater.
The oil in your system will remain there if you purge the gas slowly.
It would require that the system be pumped down to a vaccum, not only to aided in the inital charging of the gas, but to dry the system of any moisture that may be present. You can charge the system without pumping it down.
The pressure gauge has a colored scale indicating when you are at the right pressure.
Don't doubt yourself, just do it.
Happy Trails beep Beep from The Spiderman in Houston!!!

If you have studied a/c systems or watched a pro service a/s systems you may want to tackle it yourself. You can buy a Haynes A/C and Heating Systems manual and a Professional type manifold gauge set. If the pressures are not normal you can seek professional help. If you need to open the system to replace parts you need a pump to evaporate any moisture in the system. The pumps are expensive. It will eventually kill the system if moisture is left in the system. The r134 professional gauges are not that expensive, especially if you want to experiment and learn. If you read up on it,it is not rocket science. Have fun.

__________________
1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T

Thanks for the replies.


I evacuated the r134 and replaced it with 36 oz of r134. It works again although not as cold is i would like but i am done playing with it. I will have to accept that R134 will not cool down as cold as R12. Now to even bigger projects. My auto climite control does not work all that great. I get no air from the central vents, my fresh air vacuum element and my foot vents never acutuate. The proir owner replaced the climate controls about three years ago so i hope it is not the unit. Now it is me and my litte vacuum tester. This one is not going to be easy. when i figure it out i will let everyone know how to do it. So far I am considering replacing the vacuum lines as they come into the car.

It gets pretty complicated... I will let you know how it goes.


thanks again for your support.

sometimes i wonder if i should buy a new vw diesel. I wouldnt spend so much time and money repairing it. But i must say that my old benz would kick a new vw but in a fight. (after i catcht up to it)

bye

bobo

Bob. On my '85 300D I have gone through some of the actuators with the mighty vac. The following actuators work: center vent, defrost main and recirc. I have not tried the foot area actuator but need to. I ended up replacing the recirc actuator. Funny thing about the recirc actuator - after replacement it works but if you put the tester on it it "bleeds" off the negative pressure. It is brand new so I guess it is designed like that. Keep me posted on your troubleshooting and I will do the same. I did find the linkage disconnected on the center vents. Also, get a copy of the "Electrical Troubleshooting Manual" from the MB 800 number for this car. It has all the schematics for the vacuum system too.

__________________
Jim

I am a cursed man

While trying to diagnose my vacuum problem I shorted out my control unit. The profanity was brutal to the ears. I am ashamed of myself. But I am also a forgiving man and and I am already forgiven.

Word of advice dont short these things out they are expensive. Here is the good news

This gives me the opportunity to rebuild the system.
Here is what I ordered.

1 new 6 prong vacuum fitting. (which goes from the green line to the switchover valves
5 new switchover valves (I think that one of them were broken so I will replace them all)
One new check valve for the center vent
1 new vacuum element for the defroster vent
And 1 brand new control unit $$$$$$

I am also probably going to run new vacuum hoses to the elements. or at least change out the connections.

Luckily for me my brother works in the parts department at Mercedes benz and i can get this stuff at cost. Even still it will cost about $300.

By the time I am done I should be an expert on the subject and able to help others from my mistakes. That $300 would have been 3 sessions with a therapist. I am wondering where my brake even point is.

Thanks for all your help.

bob

What did you do to short it out Bob?

__________________
Jim

I was pulling off the vacuum hoses from the switchover valves that go to each circuit(1-5). The two wires that go to the switchover valve came loose and made contact. and next thing i know sparks fly and that nasty faint smell of circuit board. I wanted to see if the switchover valves were working and if the control unit worked in all of its functions. Now after that the control unit does not work at all. Am am asuming that i fried it. I hope that is all that got cooked.

THanks for all your help

bob

Brother of the Benz, The Bob
I know there is method to ones methods or madness, but why were you working in an area so confined and subject to electrical components and did not disconnect the battery?
I too, as so many of us have done, experienced the power of that balankety blank 12 volt killer the battery.
Working as you were, I shorted my watch band between 12 volts and ground.
I couldn't get free of the short and couldn't get the watch off and screaming while the flesh burned and stunk.
It gave me a cute little third degree burn.
The Doctor said I was fortunate it didn't cook an artery at my wrist.
But anyway, I didn't fry any electrical components.
Happy Trails Beep Beep from The Spiderman in Houston!!!

P.S. The watch was my Rolex I purchased on Holiday in Hong Kong. The band still has it's battle scars.

Hey spiderman

Thank you for sharing your grief. A third degree burn is brutal. I usually take off my rings and watches but now I will always do it. THe worst part was that I was just messing around with it. I was not prepared at the time to fix it. Anyway I have alot of egg on my face for this one. I replaced all of the fuses with the hope that it may have blew one out but no luck. So I took it out of the car and dismantled it and not so suprising was a quarter sized black spot with little pieces of wire sticking out of it. I cooked alright... at least there can now be closure. I can move foward to more complex undertakings. My friends said that I would not be able to work on the mercedes, that they were expensive to maintain and may be over my head. Well I'll show them.

Thanks for your replies

I dont feel so alone with my habit for destruction.

bob

no kidding it is genetic. My father did this to me and I will pass it along to mine. I used to have to hold the drop light and get him a 12mm open box wrench every saturday. THe worst thing he did was put a bus diesel oil filter on a wonderful 81 vw dasher diesel(He was a bus driver in New York). 40 miles later my mother blew the engine up going over the george washington bridge in NYC. That car was never the same. He killed a great car to save $5