Performed routine maintenance on 4 trane systems. Found dirty 20x22 filters in all of the units. Checked filter, checked thermostat, checked elements and blower amps, checked the evaporator coil, checked drain pan and blew out the drain line, checked/tightened electrical connections, checked capacitor, checked fan and compressor amps, checked pressures and reversing valve, cleaned condenser coil Client is ordering filters to be put in ASAP