Brand: Honeywell
Category: Thermostat
Manual Type:
Language:
Manual for TH8320U - Troubleshooting and error codes + PDF Download
Uploaded: April 8, 2025, 1:45 p.m.
Manual Publish Date: 2004-01-01
Warranty Summary
No warranty information found in this manual.
System Settings:
- Heat: Controls heating system.
- Off: Heating and cooling off.
- Cool: Controls cooling system.
- Auto: Automatically changes between heating and cooling.
- Em Heat: Emergency heat for heat pump systems.
Fan Settings:
- Programmable for each period (Wake, Leave, Return, Sleep).
LED Indication:
- Indicates Emergency Heat mode or system check/fail signals (requires 24Vac common wire).
Preprogrammed Settings:
- Default program settings are available, see table in manual.
Troubleshooting and error codes
| Symptom | Possible Cause | Action |
|---|---|---|
| Display does not come on. | Thermostat is not being powered. | Check for 24 Vac between C and Rc. Check that AAA batteries are installed correctly and are good. |
| Temperature settings do not change. | The upper or lower temperature limits were reached. | Check temperature setpoints. Check Installer Setup Numbers 0600 and 0610; modify as needed. |
| Heating or cooling does not come on. | The keypad is fully locked. | Check Installer Setup Number 0670 to change keypad locked options. |
| Heating or cooling does not come on. | Thermostat minimum off-time is activated. | Wait up to five minutes for the system to respond. |
| Heating or cooling does not come on. | System selection is not set to Heat or Cool. | Set system Selection to correct position. |
| Heating or cooling does not come on. | O/B terminal is not set correctly (Heat Pumps only). | Check Installer Setup Number 0190 and set correctly. |
| Heating or cooling does not come on. | System type Selection is incorrect. | Check Installer Setup Number 0170 and make sure correct System type is chosen. |
| Thermostat is calling for Heat (Heat on) or Cool (Cool on) but no heating or cooling is running. | Heating or cooling equipment is not operating. | Check wiring. Check Installer Setup Number 0170 and make sure correct system type is chosen. Verify operation of equipment in System Test mode. |
| Thermostat does not respond when touch areas are pressed. | The keypad is locked. | Check Installer Setup Number 0670 to change keypad locked options. |
Troubleshooting and error codes
| Symptom | Possible Cause | Action |
|---|---|---|
| Display does not come on. | Thermostat is not being powered. | Check for 24 Vac between C and Rc. Check that AAA batteries are installed correctly and are good. |
| Temperature settings do not change. | The upper or lower temperature limits were reached. | Check temperature setpoints. Check Installer Setup Numbers 0600 and 0610; modify as needed. |
| Heating or cooling does not come on. | The keypad is fully locked. | Check Installer Setup Number 0670 to change keypad locked options. |
| Heating or cooling does not come on. | Thermostat minimum off-time is activated. | Wait up to five minutes for the system to respond. |
| Heating or cooling does not come on. | System selection is not set to Heat or Cool. | Set system Selection to correct position. |
| Heating or cooling does not come on. | O/B terminal is not set correctly (Heat Pumps only). | Check Installer Setup Number 0190 and set correctly. |
| Heating or cooling does not come on. | System type Selection is incorrect. | Check Installer Setup Number 0170 and make sure correct System type is chosen. |
| Thermostat is calling for Heat (Heat on) or Cool (Cool on) but no heating or cooling is running. | Heating or cooling equipment is not operating. | Check wiring. Check Installer Setup Number 0170 and make sure correct system type is chosen. Verify operation of equipment in System Test mode. |
| Thermostat does not respond when touch areas are pressed. | The keypad is locked. | Check Installer Setup Number 0670 to change keypad locked options. |