Alternator replaced then no cool air conditioning?

[msmsms]

I've searched the threads though haven't found an answer to this one - apologies if it is hidden somewhere.

We just had our alternator replaced by the Mazda dealer on our 2002 Protege5 and now when you put on the air conditioning it doesn't blow cold air. Just coincidence or is there something they could have done accidentally?

Thanks in advance.