Fiesta Heater Problem

[tomi14robie]

Hi,i own a 2001 ford Courier van,it is a Fiesta based van,1.8 td di,a couple of month ago i replaced the heater valve and the heater has been working fine,the problem is when travelling on m ways if the heater is on full hot it wont turn down,even when switched to full cold,if i pull in to fuel the van up or stop for 10 mins it then goes to cold when told to do so?
The van uses no oil or water,is it possible when the car develops more pressure in the water system because of travelling at a steady 70 m way speed and wont allow the "gate" in the heater valve to close?Is there a cure?
thanks guys,you nearly always come up with a brilliant theory/answer
tom

 

[Burnerman]

Tom, I think its time to investigating replacement of the heater control switch on the lower dash....as far as I know, it sends a pulse signal to the stepper motor that opens and closes the heater water valve and they are known to fail, but not to the ridiculous frequency of the valve itself!
I haven't known the valve to partially fail - for me it either works or it doesn't, but you could try not turning the heater quite fully on to see if it makes any difference.
It could be worth investigating second hand parts from the like of ebay, and of course if I am wrong, then I'll happily emigrate
John

 

[Mursal]

I've been to Australia several times ........

 

[tomi14robie]

Thanks for reply Burnerman,the valve i fitted was a new one from my local motor factor,i may look for a heater controller at my local scrapyard and see if that will work,thanks again
Tom