SOV? what is that and where is that? i just checked my lines......i replaced most of the rubber tubing that connect the lines bec they were old and brittle...found one part that seems really worn out, a valve of some sort on the passenger side in front of the firewall. i ordered it and will pick it up tomorrow, but if i blow in it i get air out of the other end and if i blow in the other end....i still get air! lol. same as the piece that allows for my a/c and heater to run at the same time. i just need to save up the money to buy that piece, not really a priority now, now that the summer is over.