Air Conditioning problem on 89 300 SEL
 

The air conditioning in my 89 300 SEL is not very cold. Cool at best! I am taking it in to have Freon put in. The shop says I have to have a "leak check" first. I bought this car, and know the original owner. It has never had any additional Freon added. Is the "leak check" necessary or unnecessary expense?

Any idea what I am looking at cost wise?

A leak test should be pretty straight forward and not too expensive. They should have a meter that they move around all the hoses, connections and compressor that should signal if there is a significant leak. If none has ever been added and nothing has ever been done to it you may just need a good shot of r12 to clear the sight glass. Get whoever you take it to to show you how to look at the sight glass to determine low charge. Anyone should be willing to show you how to do that.

What ever you do keep it a R12 system. You will be happier with that.

Hmmmm, this sight-glass thing seems to be misleading, at least to me. When my '91 was brand new, and cooling like crazy, the glass had a foamy, moving liquid look to it. No big bubbles, you could just see the liquid moving by in sort of a foamy-looking state, at any RPM.

After 12 years, it started to not cool so well, but the sight glass had that exact same look - sorta foamy liquid going by.
I did a pressure check, found it a bit low, and added one can of R-12 from my secret cache. The pressures came right up and it cools great again - but the glass still has that old familiar foamy look.

So I learned nothing from the sight glass. But I must admit that one can of freon in 12 years ain't too shabby.