Can't get return lines and skimmer to blow out

[weatherillgrp]

I have winterized my pool for 8 years. This year, following the same process as previous years, I can't get the return lines and skimmer to blow out. I drained the bottom of the filter, replaced plug and put the multi port valve on winterize. Attached shop vac on the backwash outlet on filter and attempted to blow out lines. As done in previous years I close the skimmer valve and plug one of the two returns to maximize pressure on the only open return line. It tries to purge but there is not enough air pressure to blow it out. It seems as though something is blocking full air from getting through the line. Block that return and opened the other but got same results. If I open the skimmer valve and try to blow it out the same happens. Any suggestions would be appreciated.

 

[Catanzaro]

replaced plug and put the multi port valve on winterize

Place multi-port on "recirculate", not winterize. Only when you are done with everything and you have drained your filter, then you move to "winterize". Unless I missed something, this is what you stated, correct?

Also, I have never heard blowing out through the backwash line. Are you sure, that in the previous years, you set it on "winterize?" Why not create an adapter out of your skimmers, if not possible at equipment pad.

Is it possible you also have to place the multi-port on backwash and try blowing out through the system. I would try both to see which one works.