Many car-makers of this era were fitting stereo systems with security codes to deter thieves who were having a field day at the time breaking into cars to steal the radios. The idea was that without the security code, the stereo wouldn't work and was, therefore, useless to the thieves. So why steal it in the first place?

Great theory, but in practice, these codes have become a nightmare for subsequent owners. That's because every time you need to change the car's battery, the stereo has to have the security code re-entered before the radio will work again. If that's what's happened in your case, then you need to search through the glove-box for all the original owner's manuals and delivery documents to see if you can find the code (usually a four or five-digit number). If you can find it, great, you simply punch it into the stereo and it should be off and running again.

If you don't have the code, you'll need to contact Ford's customer service division or even a dealership. In some cases, they can quote you the security code over the phone (if you can convince them you're the car's legal owner) and you've provided the car's VIN. What's also possible is that they'll need the serial number of the actual radio which usually means removing it from the dashboard.

The cold starting system isn't working; it's probably not getting the correct fuelling at the start, so check the sensors to make sure they're working.

The control for the heater/air-conditioning system in those model Falcons is notoriously unreliable. I would be looking there to find the fault, it probably needs replacing.