I am in apartment with old Lennox system. Came home after leaving thermostat on cool/auto and part in wall (compressor?) was running but fan over hall closet not blowing any air out. I thought circuit tripped but noticed when on auto sometimes the fan would come on with compressor and at other times not. The landlord has had someone replace the fan motor and now the thermostat but it's still doing it. What's left? It's been almost a month and I'd like to get some sleep, LOL.

Replace A/C fan relay.