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T7351 COMMERCIAL PROGRAMMABLE THERMOSTAT
63-2666—02 18
Heat will not come
on.
No power to the thermostat. Check that X terminal is connected to the system
transformer.
Check for 24 Vac between X and RH terminals.
If missing 24 Vac:
• Check if circuit breaker is tripped; if so, reset circuit
breaker.
• Check if system fuse is blown; if so, replace fuse.
• Check if the HVAC equipment power switch is in the Off
position; if so, set to the On position.
• Check wiring between thermostat and HVAC equipment.
Replace broken wires and tighten loose connections.
If 24 Vac is present, proceed with troubleshooting.
Thermostat minimum off time is activated. • Wait up to five minutes for the system to respond.
• Configure heating response.
System selection is set to Off or Cool. Set system selection to Heat or Auto.
DAT high limit has been reached, or
OAT lockout is engaged.
• If the setpoints are correct, do nothing.
• Adjust or disable DAT high limit and/or OAT lockout.
• Check HVAC equipment to ensure proper operation.
Cooling will not
come on.
No power to the thermostat. Check that X terminal is connected to the system
transformer.
Check for 24 Vac between X and RC terminals.
If missing 24 Vac:
• Check if circuit breaker is tripped; if so, reset circuit
breaker.
• Check if system fuse is blown; if so, replace fuse.
• Check if the HVAC equipment power switch is in the Off
position; if so, set to the On position.
• Check wiring between thermostat and HVAC equipment.
Replace broken wires and tighten loose connections.
If 24 Vac is present, proceed with troubleshooting.
Thermostat minimum off time is activated. • Wait up to five minutes for the system to respond.
• Configure cooling response.
System selection is set to Off or Heat. Set system selection to Cool or Auto.
DAT low limit has been reached, or
OAT lockout is engaged.
• If the setpoints are correct, do nothing.
• Adjust or disable DAT low limit and/or OAT lockout.
• Check HVAC equipment to ensure proper operation.
System indicator
(flame: heat,
snowflake: cool) is
displayed, but no
warm or cool air is
coming from the
registers.
The call for heat or cool is not yet given. Check if any stage indicators (dots next to the system
indicator) are displayed. With no display of stage indicators,
no call for cool/heat via relay is yet given.
Conventional heating equipment turns the fan
on only after the furnace has warmed to a
setpoint.
Wait one minute after seeing the on indicator and then
check the registers.
Heating or cooling equipment is not operating. Verify operation of heating or cooling equipment in Test
Mode.
Table 11. Troubleshooting Information. (Continued)
Symptom Possible Cause Action