Yes it was the heater control valve. The car went in to have the catalytic converter replaced and when my partner went to do the weekly check she found there was hardly any water in the rad. The garage had snapped the heater control valve (how you can snap that i don't know) the garage put a ford ka one on from one they were selling and it turned out to not work it was always stuck on the open position.
Hi We have a similar problem. We tested the voltage and we have 12 volts on hot and 12 volts on cold (but still blowing out hot) We tested a neighbours fiesta and his is 12 volts hot and cold. Were the pollen filter is the air temperature when the blowers are on is really cold. We removed the pollen filter which was block with dust and dead flies and this made a slight difference. I think we will have to pull the hot and cold switches apart and have a look to see if it is working properly. Regards Eldon