Where is electric waterpump motor for heater on 2000 Jag xk8. Does it runs all the time the heater is on?

here is a pic of what i think you want/need. if the core is plugged just hook up a hose from your house to the outlet and back flush it, that should take care of it.

Thanks, I have ordered a manual to help with future problems. I retired from fixing Jags almost20 years ago and I know the older ones very well. I found an xk8 when in Florida on holidays and bought it.It is very much a different car now, some stuff is much the same under the skin, but so much is now electrical.
Thanks again

one other thing is to check the actuators in the heater unit they control temp and air flow so one may not be working causing the no heat problem. if your heater hoses are hot on both sides then that may be the problem.