Upon arrival for service system on and cooling poorly. Inspected system and found refrigerant low. Leak searched and found leak in evap coil. Added free pound of refrigerant and pressure returned to functioning levels but still slightly low and risks leaking back out. Fan and compressor amp draw within unit specifications. Coil heavily corroded. Dust and growth on blowers. Capacitor within tolerance. Drain line clear. Due to cost of repairs and age of system recommended speaking with engineer. Customer agreed and scheduled for Thursday July 13th 6-8.