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Heater Problem (Not The Valve)


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Sorry this is my first post and I'm asking a question. I promise, where I can, to contribute some help to others to maintain the balance... :)

I have a 1999 fiesta (I think it's a MK4 - the type with the facelift) and have a problem with the heater control. A while ago it started blowing hot only. The air con still worked but hot was all I got. So I changed the valve (it's now on its 5th valve!) but still it blew hot (my fault really, I should have checked the voltage across the valve terminals before assuming it was the valve at fault). After a bit more checking I decided there must be a fault with the control PCB (couldn't find any earth faults or any other potential causes) so I bought a replacement PCB from the scapyard for £5 and all was well... for 3 weeks... now I'm back to hot air only :(.

Strangely enough the air con switch no longer works at all. I'm wondering if this PCB has now blown too. If it is the PCB does anyone know how I find out the cause? I don't want to fit another just to have it blow on be again in a few weeks.

My interim plan is to hard wire the heater to blow cold, at least for the summer months! I will miss the air con though. It's a shame as the air con has never been re-gassed and still blows really cold. Way colder than most cars my wife's had since I "inherited" the Fiesta.

Any help would be appreciated greatly.


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Found the cause. The dupont connector has a loose connection on one of the pins so I've pushed a stiff wire in to run alongside the pin and it's working now. Shame the connector can't be stripped easily to tighten the connections.

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