1999 Ford Fiesta MK 4 - Heater valve faulty?

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Sat 12 Sep 2015 09:00
1999 Ford Fiesta MK 4 - Heater valve faulty? - Calum_y

Recently been having trouble with the whole cooling system, first my thermostat seized up, then several of the pipes blocked up so the rad wasnt warming up and then my heater valve wasn't opening. So i went and fixed all this as well as my car door (the fish eye on my passenger side outer had snapped, awaiting replacement) but after testing etc I've discovered the new heater valve is stuck open, Everything else is fine, pipes are warm, rad is warm no overheating etc. When i change my temperature dial I can't feel or notice any movement in the valve itself, do you think the replacment unit is faulty? any other way to test? I'm guessing take it off and leave the motor attached see if it moves. Or could it be the motor?

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Sat 12 Sep 2015 15:41
1999 Ford Fiesta MK 4 - Heater valve faulty? - elekie&a/c doctor
The heater valves on these are fully open at rest,or with the plug disconnected.So you should have full heat if the connector is removed.Operating the heater control temp knob pulses the valve to full shut when cold selected .If there is no heat with plug off,either you have an air lock or the heater matrix is blocked.Bleeding air out of the cooling system can be aright pain on these.
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Sat 12 Sep 2015 19:54
1999 Ford Fiesta MK 4 - Heater valve faulty? - Calum_y
No the heating is on. It won't turn off. They new heater valve won't close.
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Sun 13 Sep 2015 00:08
1999 Ford Fiesta MK 4 - Heater valve faulty? - elekie&a/c doctor
So you will need to check power to the valve,ignition on,One of the pins should be permanent ignition voltage,the other is the earth return back to the heater control valve,which should change as the control is rotated.If there is no change,then I would suspect the heater panel is at fault.A new one is around £300,so a s/hand unit will be the best option.However if there is a variation in voltage,then it is likely your valve is faulty.
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Sun 13 Sep 2015 08:19
1999 Ford Fiesta MK 4 - Heater valve faulty? - Calum_y
Guessing I need a multimeter to test the voltage? Or should there also be a visible change?
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Sun 13 Sep 2015 09:28
1999 Ford Fiesta MK 4 - Heater valve faulty? - Railroad.
Heater valves on these models are made of plastic. You may find that the old one broke as you took it off, and the broken pieces are now blocking the new valve from closing. That's happened to me a couple of times. Take the new valve out again and make sure there's nothing jammed inside it. Also flush the heater matrix in both directions to make sure it's clear.
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Sun 13 Sep 2015 10:56
1999 Ford Fiesta MK 4 - Heater valve faulty? - Calum_y
I'll have a look tonight once I finish work. How exactly do you flush it both ways?
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Sun 13 Sep 2015 11:42
1999 Ford Fiesta MK 4 - Heater valve faulty? - Wackyracer
I'll have a look tonight once I finish work. How exactly do you flush it both ways?

Disconnect both hoses that go to the heater matrix and use a hose pipe on each one alternately until all dirt and debris stop coming out.

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