Ford’s electrical systems are generally reliable, and the Mondeo is especially good.
But, like other Mk2s, the ST24 is prone to faults with electric windows (make sure all four go up and down) and central locking motors: so ensure they all lock and unlock on the key. It’s common for individual door motors to fail, and although they’re available second-hand, old Mondeo parts won’t be around forever.
The dashboard may also be a source of concern, with warning lights having a disco – the ABS lamp may stay on (probably due to a dirty or faulty wheel sensor), and airbag warnings could be caused by a poor connection in the loom under the front seat.
Check the charging lamp (battery symbol) comes on with the ignition, goes off when the engine starts, and doesn’t light up or flicker under high revs, which points to alternator failure. Turn on the headlamps, heater and other electrical gadgets, and see if it comes back on. The alternator is awkward to replace because it lives at the back of the engine beneath the rear exhaust manifold.
Alternator failure may also show up in symptoms such as pulsing or flickering headlamps – but a broken alternator wire may equally be to blame, which is a cheap and simple repair. Likewise, the cause could simply be a duff battery. Check the engine is easy to start from cold, but bear in mind ST24 starter motors sound lazy before they wear out.
A heated windscreen was standard on the ST24, and elements are prone to failure – which isn’t easy to check unless it’s a cold day. All Mk2 Mondeos have problems with the heater blower, which are usually a simple fix but could make a good bargaining point; make sure it works on all settings, and test the air conditioning gets cool.
Most importantly, Mondeo twin cooling fans have a habit of seizing solid, with a cooked engine being an eventual consequence. Allow the engine to get warm, and listen for the cooling fans cutting in. If not, they’ll need replacing ASAP.