Honeywell TB6575B1000/U Installation Instructions - Page 17

TB6575/TB8575 DIGITAL FAN COIL THERMOSTATS TROUBLESHOOTING Table 8 provides troubleshooting information. Table 8. Troubleshooting. Symptom Possible Cause Action Display does not come on. Thermostat is not being For TB6575A/B, check for 120/240 Vac between L and N. powered. For TB8575A, check for 24 Vac between R and C. Temperature settings The upper or lower do not change. temperature limits were reached. Check the temperature setpoints for heating and cooling (Installer Setup codes 16 and 17 respectively). Modify as needed. The keypad is fully locked. Change keypad locked options (Installer Setup code #18). Heating or cooling does not come on. System Type selection not Set the Installer Setup code #2 (System Type) to the correct value set to Heat or Cool or the to match the installed heating and/or cooling equipment. Verify selection is incorrect. operation of wiring and equipment in Installer Test mode. Thermostat is calling Heating or cooling for Heat (Heat on) or equipment is not Cool (Cool on) but no operating. heating or cooling is running. Check wiring. Check that the Installer Setup code #2 (System Type) value matches the installed heating and/or cooling equipment. Verify operation of equipment in Installer Test mode. Heat does not turn on Heating equipment failure. For TB6575A/B: (Heat On is solid in 1. Check for 120/240 Vac at the equipment between power and the display). common, (terminals L and N). 2. Check for 120/240 Vac between the heat (W) and common (N) terminals. If 120/240 Vac is present, the thermostat is functional. For TB8575A: 1. Check for 24 Vac at the equipment on the secondary side of the transformer between power and common (terminals R and C). 2. Check for 24 Vac between the heat terminal (W) and transformer common. If 24 Vac is present, the thermostat is functional. Loose connection or broken wire between thermostat and heating equipment. If voltage is present, check the heating equipment to find the cause of the problem. For TB6575A/B: Check for 120/240 Vac between the heat (W) and common (N) terminals. For TB8575A: Check for 24 Vac between the heat terminal (W) and transformer common. If voltage is not present, check wire connection (loose or broken) between the thermostat and the heating equipment. Both the heating and Incorrect System Type Check that the Installer Setup code #2 (System Type) value cooling equipment are selected. matches the installed heating and/or cooling equipment. running at the same Heating and cooling wires Separate the shorted heating and cooling wires. time. are shorted together. 17 62-0311-05