I went through the troubleshooting charts in the 'Installation Instructions'.

The FAN CHECK ONLY flow chart indicated the thermostat was bad. Replaced thermostat. A/C compressor comes on-no blower. Heater lights fine & finally shuts down-no blower.

COOLING CYCLE CHECK and MAIN BURNER troubleshootin flowcharts indicate bad module even though the FAN ONLY CHECK still shows a bad thermostat.

ARRGGG! '