Flushing Air conditioning - 560SEL
 

Is it possible to flush the low side with the expansion valve connected?

I removed the ac compressor and dryer today and flushed the high side with very little residue to speak of. the flush fluid was clear that I can see. I poured it through the hose (top side) and pushed it through using air compressor.

The AC compressor is totally empty, and the o-rings (6 black in color) appears to be in good shape.

I removed the panel below the steering wheel and visually, I found the exp valve to be dry and clean without any traces of any leak, so I thought I would leave it alone. I was planning on flushing the low side and just push it with air, perhaps mid psi ( not too high).

Just flush it all, it is a waste of time not to since the system is open. It would be like taking a shower and only washing yourself from the waist down.

Best way to flush evap core is to remove the exp valve, drill a small hole in the liquid line, reinstall, then flush from under the hood.