A/C blows cool air sometimes on 2006 Infiniti M35

A/C blows cool air only on certain fan speed settings then blows warm air after about 5 minutes. Cool air may come back on after changing fan speed setting multiple times. Auto setting only works sometimes. There is a wierd smell sometimes in the air flow when it blows warm air. Sometimes fan speed at higher setting will change to higher speed when the setting is NOT on Auto. I've had problem about 2 weeks.

Could be the relay, there shouldn't be any problem getting a replacement part as these are generic in nature. If it is the controls, that would be a different matter. Without any proper diagnostics, it is not possible to determine if the diagnosis is correct or not.