Mk5 Heat Problem

[VibrantSeeker94]

I've heard and read that fiesta MK4 and MK5s can have a heat problem with either hot or cold constantly feeding through and not being able to change the temperature. Mine is doing the exact same.

It's feeding through constant hot air. After having read a solution, I thought it could be a thermostat problem. The guy I bought the car from told me he'd already changed that not so long before I bought the car and it was bought in March.

I then read it could be a heater control valve problem. I changed the heater control valve and it worked! For a day or two... No I'm slightly stumped as to what next to look for.

I don't believe it could be the matrix.

I don't think there is a blockage anywhere otherwise it wouldn't have worked as soon as it was swapped.

I'm reluctant to think its the connection as I checked that while swapping over the HCV and it seemed OK. Plus, it wasn't all that long ago.

There's definitely no Leaks.

The head gasket hasn't gone and its not on its way out.

A few people had mentioned the heater control panel might be an issue. The fans are working on all settings but there's no wires running from the temperature knob. It's all running from the fan switch, the bottom of the PCB board and the 12v power supply. I don't think it could be the HCP neither becauxe it was working g when the HCV was swapped over. And I'm sure the wiring is normal anyhow.

Has anyone got any ideas? I've searched all over this forum and I can't seem to find the answer. I'd rather not take it tons mechanic and part with my money haha.

Thanks guys.

[supersteve]

Hi fiesta guys, I had the same problem on my ford fiesta 2000. Constant heat and no temperature control. the problem turned out to be a badly corroded heater control valve. Do not buy cheap imitations these do not last,better off buying a ford original part. second problem,when the heater valve is knackerd this shorts out and burns up a copper print track on the heater control panel,this can be easily repaired or if you have loads of money available from your local ford dealer

happy days Supersteve