I have one zone on a 6 zone clock which will not run for the allotted time. I have switched the wiring from one zone on the clock to another and that did not change anything. I have switched things around until the only thing that remains the same is the zone valve. Why would a zone valve shut off after 2 or 3 minutes when it is scheduled for 20. This is an older system that has been working properly until recently. Thanks for your help.
