Honeywell T7351 Product Data page 18

T7351 COMMERCIAL PROGRAMMABLE THERMOSTAT
Symptom
Heat will not come No power to the thermostat.
on.
Thermostat minimum off time is activated.
System selection is set to Off or Cool.
DAT high limit has been reached, or
OAT lockout is engaged.
Cooling will not No power to the thermostat.
come on.
Thermostat minimum off time is activated.
System selection is set to Off or Heat.
DAT low limit has been reached, or
OAT lockout is engaged.
The call for heat or cool is not yet given.
System indicator
(flame: heat,
snowflake: cool) is
displayed, but no
Conventional heating equipment turns the fan
warm or cool air is
on only after the furnace has warmed to a
coming from the
setpoint.
registers.
Heating or cooling equipment is not operating. Verify operation of heating or cooling equipment in Test
63-2666—02
Table 11. Troubleshooting Information. (Continued)
Possible Cause
18
Action
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.
• Wait up to five minutes for the system to respond.
• Configure heating response.
Set system selection to Heat or Auto.
• If the setpoints are correct, do nothing.
• Adjust or disable DAT high limit and/or OAT lockout.
• Check HVAC equipment to ensure proper operation.
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.
• Wait up to five minutes for the system to respond.
• Configure cooling response.
Set system selection to Cool or Auto.
• If the setpoints are correct, do nothing.
• Adjust or disable DAT low limit and/or OAT lockout.
• Check HVAC equipment to ensure proper operation.
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.
Wait one minute after seeing the on indicator and then
check the registers.
Mode.