Wiring Diagrams - Honeywell T7350 Installation Instructions Manual

Symptom
Cooling will not No power to the thermostat.
come on.
Thermostat minimum off time is
activated.
System selection is set to Off or
Heat.
System indicator The call for heat or cool is not yet
(flame: heat, given.
snowflake: cool)
is displayed, but
no warm or cool
air is coming from
the registers.
Conventional heating equipment
turns the fan on only after the
furnace has warmed to a setpoint.
Heating or cooling equipment is
not operating.
WIRING DIAGRAMS (FIG. 7 - 14)
SUBBASE
L2
1
L1
(HOT)
HEATING
TRANSFORMER
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2 WHEN INSTALLED ON A SYSTEM WITH TWO TRANSFORMERS, REMOVE THE FACTORY-INSTALLED JUMPER.
Fig. 7. Typical hookup of T7350A in two-stage heat and one-stage cool conventional system
Table 4. Troubleshooting Information. (Continued)
Possible Cause
with two transformers.
T7350 COMMERCIAL PROGRAMMABLE 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.
• Wait up to five minutes for the system to respond.
• Use PDA to configure cooling response.
Set system selection to Cool or Auto.
Check if any stage indicators (dots next to the system indicator)
are displayed. With no display of stage indicators, no call for
cool/heat is yet given.
For T7350M models only: Check the information screens. A
MODHEAT or MODCOOL percentage of zero indicates a signal
of 4 mA from the given terminal.
Wait one minute after seeing the on indicator and then check the
registers.
Verify operation of heating or cooling equipment in self-test.
2
X RH RC AUX W1 Y1
HEAT
RELAY 1
COMPRESSOR
HEAT
CONTACTOR 1
RELAY 2
9
Action
G
FAN
RELAY
L2
1
L1
(HOT)
COOLING
TRANSFORMER
M19764A
62-0195—04