Siezed AC Compressor, Expansion valve needed
 

I siezed the AC compressor on my 560SL. I have a new compressor and receiver drier to install. But lately I have been reading many compressor overhaulers insist on flushing and replacement of the expansion valve. 18 years ago when I worked on these cars for a living I never heard of this and never did it. How important is this. It is a 1988 560SL with an Aluminum compressor R-12 system.

John Roncallo

Most shops flush the entire system in case metal fragments entered the system from the failing compressor.

I have flushed several systems due to failing compressors and in most cases there was metal slurry in the oil in the system.

Most shops do it just to cover their butt.
Better to be safe than sorry.
I would spend the extra time and money to flush the system.
We used and alcohol based solution, the name escapes me, but we filled a metal cyllinder with this stuff and flushed the systems out with this stuff hooked up to compressed air, and it dried the lines as it cleaned all the oil and metal debris out of the system.

I'm sure someone on here will know what it's called.
If you have alot of oil and metal fragments in your system, you may risk contaminating your system.

Can it be flushed with the expansion valve installed. I have flushed the AC on my Ford Taurus but the orfice tube was reboved when I did that. The 560SL has the expansin valve under the dash.

John Roncallo

Need to remove/replace the expansion valve, or the little needle valve will jam up with crud.

Many compressor warranties require new R/D and new expansion valve.

The part is quite inexpensive, maybe $25 at the very most. I'd do it, also you'll be able to install new o-rings while it's out. Not to metion like others have said, it can clog.

Here's a link that may be helpful:

http://dieselgiant.com/repairyourac.htm