JONXLR8

Hi all. Jonathan here from Brum. My first car was a 1.3 C-reg 1986 Mk3 Escort with XR3i alloys and a one off pearl paint job.... and vv carb and loads of electrical faults. Am i allowed to stay? LOL

Anyway, my mrs has got a Mazda 121 (Fiesta) which she loves driving (100% more than her old Clio).

It's recently developed a fault where the heater is only blowing cold air. It's an R(98) GXi with a 1.3 engine (is this out the Ka?), hope you can help.

I've been advised that it's this valve unit that's failed and these two threads show it as a common problem.

...but the pipes after the valve on the heater side are hot after a run, so that should mean hot water is flowing through the heater matrix, right? If the valve had failed shut, surely those pipes would remain cold?

Is it likely that the heater control potentiometer thingy has failed? I couldn't see any loose wires running to it. Does the heater dial directly control the opening and closing of the valve?

The coolant is a bit mucky but theres no leaks.

Any clues?

SafeChav

That valve to me looks like it makes the coolant re-circulate without passing through the matrix.

And to be honest thats logical, it wouldnt be good for the cooling system if pipes just got blocked off.....

JONXLR8

Oh yeh, good point. So if the valve has failed then it's failed open and is allowing the water to circulate fully through the heater and therefore i should be getting constant hot air rather than constant cold air?

So i can probably eliminate that as the fault then? Some cars have mechanical flaps in the heater system which direct the air intake through or away from the matrix dont they. I can imagine if the flap got stuck it may cause this issue but I presume this Ford system doesn't have these as the temperature is controlled by this valve thingy.

BTW, i've tried unplugging the loom to the valve to see if it makes a difference... it didnt.

Another thing i thought of was a blockage or airlock in the matrix but yet again, both pipes wouldn't be hot if that was the case i reckon.

The heater valve is quite a pricey item and i can imagine it still being fairly pricey from scrap yards (if i could be lucky enough to find one that works).

Is it possible to test the heater control panel easily enough, anyone know if that's likely to be the problem? Am i missing something else?

iansoutham

1047752 is the finis number of the heater valve from Ford. Is normally only about Ł30 (so not THAT dear).

IT almost certainly WILL be the fault. What happens is that there is a plunger solenoid inside the valve assembly which over time gums up. Disconnecting the valve will be of no use.

In the 3 1/2 years that I ran the Trade Parts Sales Dept of my Ford dealer, out of the 300+ valves we sold a year, we sold maybe 3 control units, and out of those 3, only 1 person didn't try to send it back for a control valve.

JONXLR8

Thanks for that, I'll see about getting one ordered then...

the only reason i didn't order one already is the fact that the pipes leading from the valve to the heater are hot after a run which would seem to indicate that the matrix is getting a hot flow through it and therefore should be emitting hot air? If the solenoid has stuck then surely it must be stuck open allowing water to flow? I just cant work out why it wouldn't be blowing hot air if the matrix is getting hot water.

iansoutham

It doesn't. The solenoid sticks ALMOST shut and the heat you can feel is via convection (or whatever the equivalent name is ).

I have had exactly the same many a time and as I have said, I've only ever seen 1 control panel go wrong.

JONXLR8

Great, that makes sense. Thanks for that.