System off upon arrival. Turned it on to test operation. Coupon accurately check refrigerant charge until unit was cleaned. Performed a cleaning and tune up. After cleaning unit, pressures appear to be ok at this time and correct. Did find main level zone not supplying air. Thermostat read cool on, but little to no flow to main level. Bypassed thermostat and zone opened. It appears that the thermostat is failed. Customer will pick one up and install a new one. Everything else is working normal at this time. System replacement is recommended.