Bit of a long shot, but I have a 1997 Mondeo 1.8 and the heater and air con only work on full blast. Don't have a clue but it is pretty annoying so any help is appreciated. Thanks.

 

Will most likely be heater resistor unit.

 

It is almost defo the famous heater resistor pack burnt out, ford did a modified pack and loom to sort this which mostly did.
The reason why full speed only works is due to it being the full 12v where as the slower speeds are lower voltage supplied via a resistor.
The resistor pack is from memory ?, on the actual motor itself, so look up above where the passengers feet are in the front behind the glove box area.
tabetha

 

Just googled it and yeah going to change that asap. Thanks for the replys guys!