Ford KA only blowing hot air?

I have a R reg KA so I expect these problems but this seems like it can be fixed.

It USE to blow only cold air, which is what I want. Recently it's gone back to just hot air and it's unbearable at the moment. I know how to locate the HCV but that's as far as my knowledge goes so I'm hoping someone could advise me on how to open/close the pipes/HCV or whatever, to get it back to blowing just cold air?

You need a new heater control valve as the valves are stuck open allowing hot water to the matrix. Easy DIY job to do and the valve is around £45 from Ford. Do not get a pattern one as they do not last long.

Thermostat Valve has to change very soon.