I have just fitted a new washer pump onto my vauxhall vectra 2007, the front jets are working as usual but the back window wiper jet is not passing water although the pump is sounding for this action
Swap water the feed for the front washers to rear and rear to front and see if rear washer works.
During cold weather pipe to feed the rear may have frozen, and if you tried to operated the rear washer it may have forced the pipe off a connection.
Also as you suggest might be a blocked jet.
You could also try blowing air down rear feed to clear jet
Maurice
January 2011
I'm thinking that it is a choked jet and i will have to strip it down today or there is an electrical fault in the pump???.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.