benchph1::: Probable cause, your aircon blower motor is sucking too much current or neither one of your electricals is. Its draining power directly from your battery which should not happen in the first place.

Kaya lumalakas ang ikot ng blower and other accessories alternator is doing its job. You can be sure of that the alternator is functioning well. Check the alternator belt, baka po ito ang maluwag kaya humihina pag minor ang makina. Higpitan po ng kaunti hanggang sa hindi na pumapalag ang belt.

HTH