Checked system in heat mode, discharge temp only went up to 71°. Switched to cooling and checked the pressures, system was low on charge added 1 lb. 12 oz R-410a to system. System was discharging 53° In cooling, 125° in heating. Removed line set covers check fittings, there was no oil connections for the indoor unit, checked with bubbles did not see any leaks at the unions. Found a trace of dye on circuit “A” line set connection at the condenser. Tightened and checked with bubbles. System is running properly. If this happens again recommend checking all four indoor units for possible leak.