Error Codes

The CDT controls have built-in diagnostics which display error codes on the display. This section describes the codes.

Display	Cause	Solution
“E-4 CPU TOO HOT”	Control board too hot; unit overheating or louvers clogged	Turn switch to OFF position, then back to ON; if display still shows “E-4”, the PC board is getting too hot; clean louvers and check cooling fan; if cooling fan is not working, have it replaced; once panel cools down, the controls should return to normal; if “E-4” persists, have the PC board replaced
“E-5 AIR TEMP TOO HOT”	Faulty relay, PC board, or air probe	Turn switch to OFF position, then back to ON; if display shows “E-5”, the heating circuits and temperature probe should be checked; once the unit cools down, the controls should return to normal; if “E-5” persists, have the PC board replaced
"E-6B AIR TEMP SENSOR FAILED SHORTED"	Faulty air temperature probe	Turn switch to OFF position, then back to ON; if the display shows “E-6”, the temperature probe should be checked; once the temperature probe is repaired, or replaced, the controls should return to normal; if “E-6”persists, have PC board replaced
"E-41 SYSTEM DATA LOST"	Memory scrambled	Turn switch to OFF position, then back to ON; if the display shows “E-41”, the control should be re-initialized (see Programming Section); if “E-41” persists, have PC board replaced
"E-50"	RAM Failure	Turn switch to OFF position, then back to ON; if “E-50” reappears, have control board replaced
"E-51"	NOVRAM Failure	Turn switch to OFF position, then bakc to ON; if “E-51” reappears, have control board replaced
"E-53"	EPROM Failure	Turn switch to OFf position, then bakc to ON; if “E-53” reappears, have control board replaced