The heater on our 2004 focus tdci will work when you hold the revs at about 2.5k and will get hot but when idleing its luke warm and some times cold. When driving esp at speed its just cold. There is plenty of coolent in there, no leaks, system is getting to pressure no air leaking in etc. all the hoses are getting warm.

Car doesent overheat and the needle sits at halfway all the time.

All i can think is mabye the thermostat stuck open? or water pump on its way out?

Anyone else had this problem?