Well my first thought would be loss of refrigerant but you eliminated that (you said 10.5 amps) if that were the case you'd be seeing more like 5 or less. Though. 10.5 is a bit lower (What does the sticker say the current draw should be) Partial refrigerant loss may be an issue. This takes professional help to fix.
Have you inspected the Condenser/evaporator on the OUTSIDE?
Short but true story, I have A/C only, not heat pump so that coil is the condenser always on mine.. Well the A/C started tripping the breaker.
I checked and current was in excess of 20 amps when CLICK
Went up on the roof and the dang thing was clogged with cottonwood seeds.
Removed same, and 13.5 Amps solid.. Just like the sticker says.