Hi there. I'm new on here so please be kind 😬.... I have a 2002 mk 6 fiesta with duratec engine. Heater blows cold. The engine is reaching temperature. The heater hose into matrix is hot yet the one out is warm, nearly cold. The cable is working the flap behind the o/s footwell panel. I was told by a mechanic that the matrix will most certainly be blocked. I run a tin of gunge cleaner through the system without success. The big question is.... is it a big job to swap the matrix? I 've just watched a video on here on how to remove front dash panel and stereo , presuming that's all part of the job. I'm ok with that but how much further do I have to go to remove the said matrix. Thanks in advance....👍