Arrived to HVAC maintenance. Upon arrival made my way to the indoor unit. Here the flame sensor (cleaned), ignitor, inducer motor, and blower performed within spec. The combustion analysis showed proper burning. I performed a safety inspection of the heat exchanger finding rust and pitting throughout but no cracks. I replaced the air filter with one the customer supplied. On the outdoor unit the capacitor, fan, and compressor were within spec. The refrigerant temps/pressures showed proper heat transfer but with a high head pressure. I cleaned the coil with water to bring this down. HVAC running upon departure.