AC doesnt blow cold air
 

I had it checked out by a mechanic and was told that the "A11 control unit for a/c system was faulty, not reading correct from A/C button".
What is this?
Can a regular guy with regular tools replace it, or is t best left to the dealer?
I was also told that it would require programming of the new ihka. Whats an ihka? Does the dealer need to program it?
Thanks all,
C