What Car? Q&A - Where is my Ka leaking from?
A: This sounds like a classic case of a failed heater matrix. Check the level of coolant in the expansion tank under the bonnet, and if this is low, the matrix is almost certainly the culprit.
Problems with heater matrix on Kas are known, but they're generally this type pf failure, so you can consider yourself a little unlucky. Kas are generally solid and reliable.
The part will cost you around £70 from Ford, but fitting it is fairly tricky, so expect to fork out for around four hours of labour.
Your total bill will be roughly £450 from a Ford dealership, or slightly less if you get the work done at an independent repairer.
The heater matrix sits behind the dashboard. Hot coolant from the engine's cooling system is pumped through the matrix, which acts in much the same way as the car's radiator by dissipating heat.
The heater fan blows air through the matrix when you want warm air in the cabin. If you flick the heater control to cold, air won't be sent over the matrix and you get cold air.