Hi, 

My car definitely has one of these auxiliary electric heaters set directly below the water heater matrix core within the bowels of the dashboard, but I'm not sure it's working. How could I test it? Is there a fuse or a relay somewhere that I can check? 

Thanks. 

When you say definitely...

 

Please provide the evidence which has convinced you that your car has this device fitted as standard.

Not seen one fitted to a MK1 Fabia before. 

I just changed the water matrix in the heater box under the dash, and there was an electric element underneath it. 

That's the electric element, the water core was already out on this pic. 

 

Relays and fuses are on the relay panel up above the accelerator pedal.

Lower dash cover has to come off to access. Can give more specifics later.

What size cables are coming off it?

If it was a factory installed system, relays should be in positions 8 and 9 of the relay holder, fuses in a vertical line down the right hand end:

 

If it's an electric heating element why does it look like an evaporator core?

Cos both items require air to flow through them?

Evaporator is muuuuch harder to get at.

Ok, I've just never heard of electric heaters in a Mark 1, perhaps it's a cold-climate fitment.

Yep, it was an option on diesel-engined Mk1s, not sure if it was very expensive or something. Don't hear of many.

Ok then, a simple test of resistance using the lowest scale on the multimeter will either show a reading or be open circuit.

Yep, good place to start. Measure Ohms between the brown wire and each of the other three. Should be quite a small number but I forget exactly, maybe 0.5-1.0? 

 

Did your heater matrix spring a leak? Not a common occurrence as far as I can judge by the number of threads on here.

 

Some info here on the way it works (if it is working). I vaguely remember that these pages were in an SSP about the Lupo I found linked somewhere, rather than Fabia, but I'd easily believe it's near-identical in implementation.

 

Thanks for the good information all, hope to get chance to do some tests sometime before winter sets in. 

 

With respect to Wino's question about water matrix springing a leak, it sure did. And I know why too... If you look in engine bay, take off the large diameter pipe from air box, you can see the 2x metal pipes that enter the bulkhead going straight into the water core. Follow these back up, and where they attach to rubber hoses, there's a bracket which clamps the metal pipes to car body. The bolt had sheared, causing the movement/vibrations of the engine to be transferred to the neck of the heater core where the pipes enter it. Over time this had split the neck causing a leak that worsened. Horrible job to replace the core, and the replacement core was plastic rather than aluminium,so not expecting it to last another 17 years. So if you're reading this, go out and check yours to avoid what I've been through. Cheers all.