my son used his caravan for the first time this weekend the cold tap only worked sometimes times in the kitchen and shower area but if he put on the hot tap then the cold tap would work but not on its own the hot tap was working with no problems any ideas thanks
This is a classic symptom of a faulty microswitch on the tap. If the offending tap doesn't operate until another tap is turned on, this is the usual tell-tale. The tap switches are wired in parallel so operating a good tap will cause the pump to run, then opening the duff tap allows it to appear to work.
He'll need to get under the faulty tap and check/replace the microswitch.
Hi thanks for reply but all cold taps stop not just one does this mean one tap with faulty microswitch would affect all the other cold water taps Sally
Sorry, I read as only one, but yes it's quite possible that several switches are faulty. The tap draws water on demand from the pump and caravans use either switches beneath the taps or a pressurised system. The latter rarely encounter faults such as you've described, so I can only assume your son has the switch type system in his van. As the hot tap is put on, it demands water and actuates the pump; because the pump is then running, other taps can then appear to draw water too when turned on, as pump already running from hot tap.
Best bet would be to check switches with a small multimeter set to it's 'continuity' function to check if switches ok.
One fix that can help is to remove them and soak them in a small pot of switch cleaner overnight, then allow to dry out and refit. If all else fails, replace as a job.