Heater and Air Con not working

[natben]

So time to fix my heater and air con. It hasn't worked for over a year so today I checked the fuses and they were all OK. Next it was the ribbon connector and It seems OK, so I had a look at the heater control unit in the passengers footwell and first thing I noticed is it was a 2002 unit but my car is a 98 so obviously it has been changed at some point. The wiring has also been played about with so I have decided to send it of to Python Racing so they can have a good look and repair it if necessary. Hopefully the issue is with the control unit but is there anything else I need to check.