Wiring Diagrams (Fig. 13-19) - Honeywell T7350 User Manual

T7350 COMMERCIAL PROGRAMMABLE THERMOSTAT
Symptom
Cooling will not come on. No power to the thermostat.
System indicator (flame:
heat, snowflake: cool) is
displayed, but no warm
or cool air is coming from
the registers.

WIRING DIAGRAMS (FIG. 13-19)

SUBBASE
L2
1
L1
(HOT)
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
WHEN INSTALLED ON A SYSTEM WITH TWO TRANSFORMERS, REMOVE THE FACTORY-INSTALLED JUMPER.
2
Fig. 13. Typical hookup of T7350A in two-stage heat and one-stage cool conventional system
63-2605—2
Table 16. Troubleshooting Information. (Continued)
Possible Cause
Thermostat minimum off time is activated. • Wait up to five minutes for the system to respond.
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.
Conventional heating equipment turns the
fan on only after the furnace has warmed
to a setpoint.
Heating or cooling equipment is not
operating.
HEATING
TRANSFORMER
with two transformers.
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.
• Use PDA to configure cooling response.
Set system selection to Cool or Auto.
• If the setpoints are correct, do nothing.
• Use PDA (Cooling Config) to 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.
For T7350M models only: Check the information screens.
MODHEAT or MODCOOL percentages of zero and 100
indicate an extreme signal from the given terminal. See
Table 13 for details.
Wait one minute after seeing the on indicator and then
check the registers.
Verify operation of heating or cooling equipment in Test
Mode.
X RH RC AUX W1 Y1
2
FAN
HEAT
RELAY
RELAY 1
COMPRESSOR
HEAT
CONTACTOR 1
RELAY 2
20
Action
G
L2
1
L1
(HOT)
COOLING
TRANSFORMER
M19764A