Recently my alternator packed it in and as is usual I ended up with a flat battery. After putting in a new alternator in my climate control will not heat. The cooling (air con) side of things works perfectly. But this is not much help in winter. I have tried disconnecting the battery overnight to see if this would reset the computer, but it did not work. Does anyone know what could be the problem short of replacing the unit?

Could be blend door motor and/or heater tap

Warm the car to normal operating temp, then hit the Mode and Off buttons together on the CC unit. Doing this diag resets the blend door motor travel.

It will either fix the problem, or give you an error code as to what is wrong with it.

Thanks guys, will try this out tonight and come back if it doesn't work.