My A/C is always on with the speed set to II and sometimes the fan of the A/C is not running.

I noticed the following fact.
When I turn the contact key (just before cranking) the fan is running (sometimes not), during cranking all accessories are shutted down (radio, A/C, etc.) and when I release de key all accessories are back (except for the A/C fan sometimes).

I suspect a relay to be the cause of my problem (maybe I'm wrong and suggestion will be appreciated) but I have no idea where this relay is located.

Regards,