Why didn't he ask?
 

Lindajane, I think it is terrible that he replaced a major component such as an AC system without consent, regardless of your earlier conversation. Have you contacted him to let him know that your AC isn't functioning properly anymore? Maybe a questioning call, rather than accusatory, will get you the results you desire (a working AC for the money that you spent)

My mech is like that a little too, I think it's the woman thing, how they automatically assume that you know nothing and they have to take the reins! However, when I am able to clearly describe every step of a procedure, thanks to you all here, he slows down and takes notice of what I'm saying. If I wasn't sure he's a good mechanic, I wouldn't still be with him, but I have to take control of the situation each and every time, or else.

What GreasyGriddle said is very true.... but it is also true many times if a man were to walk in and say " I want a new AC"....on a 20 year old car .... Mechanics have seen too many people who don't even know where to check the oil want them to be mind readers... and do it CHEAP at the same time.....
The more specific you can be with your mechanic the better....

Just an example
 

Last June my best friend, who is a good mechanic, diagnosed my 300D as having a bad Evaporator. $1500-1800 to fix. The system was leaking and they could not find the leak anywhere. Had to be in the evaporator.

Took the car to my local Indy who I trust 100%. He checks the A/C and tells me that it is very rarely the Evaporator, but in this case it might be since the car had been converted over to the new freon. Comes back and tells me that the compressor is leaking and is the problem. Since it is was destined to be my sons car (just turning 16) I decideded to wait to see if I was going to do anything. (he might wreck it). Guess what? Cold AC all last summer. Guess what again? Cold AC so far this year.

You just never know with these thing.

Lindajane, since you're down in LA now, and you've visited him before, take it to Enrique at MR MB Motors. He'll give you an accurate diagnosis and a solid recommendation, and he won't advise you to spend money if it's unnecessary.

Alan, perhaps your climate control amp is loose, dirty or going. It sits behind the glove compartment. My a/c did not work , much later my heat would not come on.
My mech. changed the amp and I got heat. Much to my surprise, my A/C began to work!!

I second taking the LA girl's car to Enrique.

Good luck!!

Unkl300d,

Not sure what the amp is. I know that last winter we changed a faulty mono valve and got HEAT. I do not know if that affects AC or not. The AC worked before and after that repair. I honestly thing that the leak was in the freon "intake" and it just so happens that the last time they filled it, it sealed properly.

But I am not mechanic. I am just trying to apply logic.

Yup: Enrique. Good man, great mechanic.

Believe.
 

Alan, I correct myself, if your w123 has a monovalve then it does not have the climate control amp (an electronic circuit board).
The amp was present up to 1980.
So, the Xmas elves helped you out!!
Nice.