AC performance tuneup times one system. System as a zone with an upstairs bedroom. System does not have a bypass damper. Which causes the upstairs to blow away too hard when it is the only zone calling. Treated drain lines with white vinegar. Checked thermostats for proper operations. Check outdoor unit. Refrigerant level is good at this time. Test capacitor and contactor. System is cooling properly at this time. System is 15 years old and is our 22. Recommendation is changing complete system