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Ford Fiesta Mk5 Heaters Stuck On Hot Please Help

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I bought my 2000 reg ford fiesta 4 days ago now. The heaters are stuck on hot.

I have replaced the heating control valve and i got a replacement control panel thats in the car, that you use to control the heating system. I replaced them both today and i still have the same problem.

I have also cleaned the contacts up on the plugs, incase anything had got inside them.

i dont have air conditioning. Its a simple hot/cold system

Also the previous owner had decided to cut the wire to the heater control valve (hcv) and connect the power source up to the battery, this made the blowers cold ( i assume they did this so they didnt bake). I had taken it to my mechanic and he said it may have caused a fire as the hcv would of had two much power going to it. He connected back up to the original wires, and this made the blowers blow hot. He said either part would need replacing so i replaced both. those being the hcv and the control pannel.


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I would disconnect the electrical connection to the HCV and put a voltage tester to it. Turn the ignition on and turn the heater control knob to hot. The voltage should be zero or at least very low (if I am correct the default is no power the valve opens up to allow the hot water through). Turn the control to cold and the voltage should go up to 12v.

It could be the other way round, but moving the control knob from hot to cold should change the voltage.

If this works, it must be a faulty HCV. New ones are known to fail. If there is no change in voltage, then it must be either the Heater Control Panel behing the control knob, or the power feeding to that.

The only other test is to test the voltage as above but with the engine running and the control knob set to the middle. The voltage should kick in and out if the panel is working correctly.

Good luck with it.

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Thanks a lot. my dad is an electrician, he will have that equipment.

If there is no reading, is there a way for me to by-pass the old wiring and put new wiring in, going to the control panel and the HCV.There are loads of wires going into the control panel, which two would it be?

Thanks for replying :-)

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Im not sure as it has been a couple of years since I had to sort out the one in our old Puma. If your Dads got a tester and knows his way around the electrics he should be able to find the power feed if it is working. If not, you need the wireing diagram and then find another feed to it that is live when the ignition is on.

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