Diagnosed and repaired a Lennox XC25 system with intermittent communication errors today. Found corroded low-voltage connections at the condenser causing improper communication between thermostat and control board. Cleaned terminals, applied dielectric grease, and re-terminated connections. Also replaced failing pressure transducer that was causing erratic superheat readings. System now communicating properly with indoor air handler. Ran full diagnostic tests through iComfort S30 interface - all parameters now within specification. Another happy customer in Baton Rouge!