have ya checked the direction of the valve, and how do you have it plumbed?

 

i think if the direction was wrong it wouldn't hold air period. this sounds like it's holding air, just not letting it out.

i'd replace the valve all together. but look for dirty. and take it out and see if it opens when power is applied.

 

it might have gotten a piece of dirt in one of the orphusus (sp?) pull it apart and look through every little tiny hole in the diaphram and make sure its clear

 

only one doing it?

What make model valve?

 

some valves if u have too much presure in them they lock. tap it with a scewdriver butt while u hold the switch it should open up annother thing is they need backpressure so add 6inch airline to the vale dump it should work, it did for me with my smc's