I had exactly this problem with my Galaxy. Unfortunately I took it to the local Ford dealer who diagnosed 'replace heater rheostat' and charged me £97.18. I should have come here first.
However, I didn't post just to whinge. Since that fix the heater/fan/AC unit has stopped working altogether. Also, the analogue clock (is that connected?). I have checked all the fuses and cannot see any blown.
The dealer has checked and said all lines are live into the control panel which needs replacement.
They say this will cost £400+ and there is a waiting list for the part ("obviously this is a problem part")
My questions are:
1) Is this something I could do and save myself a lot of money? (The dealer said it would only take about 30 minutes to fix)
2) Is it just a coincidence that this happened so soon after the rheostat install?
thanks for your help