Honeywell T7200 Manual page 46

T7200/T7300/Q7300
TROUBLESHOOTING
Fig. 48—Troubleshooting chart to quickly isolate a HVAC problem.
SYMPTON
HVAC WILL NOT
OPERATE.
63-4038—7
POSSIBLE CAUSE
NO ac VOLTAGE TO THERMOSTAT.
HEATING SYSTEM WILL NOT
TURN ON.
HEATING SYSTEM WILL NOT
TURN OFF.
COOLING SYSTEM WILL NOT
TURN ON.
COOLING SYSTEM WILL NOT
TURN OFF.
CHECK POWER TO FURNACE OR AIR CONDITIONER.
• ON-OFF SWITCH
• FUSE OR CIRCUIT BREAKER
• LOOSE 24 VAC CONNECTION
—AT THERMOSTAT
—AT FURNACE/AIR CONDITIONER
• INCORRECT WIRING
—CHECK WIRING DIAGRAM
CHECK VOLTAGE AT SUBBASE.
• 20 TO 30 VOLTS BETWEEN PINS 1 AND 6 ON Q7300 9 PIN
CONNECTOR (SEE FIG. 34).
—REPLACE Q7300 IF NO VAC.
—REPLACE THERMOSTAT IF VAC PRESENT.
CHECK HEATING SYSTEM:
• WAIT MINIMUM OFF TIME (2 MIN. OR 4 MIN. FOR HEAT PUMP).
• JUMPER RH TO W1 (R TO Y1 IF HEAT PUMP) AT THERMOSTAT
OR EQUIPMENT TERMINAL STRIP.
—NO HEAT, THERMOSTAT OK, CHECK HEATING SYSTEM.
—HEAT COMES ON, HEATING SYSTEM, CHECK THERMOSTAT.
THERMOSTAT CHECKOUT:
• SET SYSTEM SWITCH TO HEAT OR AUTO.
• SPACE TEMPERATURE IS LOWER THAN HEAT SETPOINT (IF
NOT, RAISE HEAT SETPOINT TO 5°F ABOVE SPACE TEMPER-
TURE).
—HEAT COMES ON, THERMOSTAT AND HEATING SYSTEM OK.
—NO HEAT, REPLACE THERMOSTAT.
•• HEAT ON, THERMOSTAT AND HEATING SYSTEM OK.
•• NO HEAT, REPLACE Q7300.
CHECK HEATING SYSTEM:
• WAIT MINIMUM ON TIME (2 MIN. OR 4 MIN. FOR HEAT PUMP).
• REMOVE RH (R IF HEAT PUMP) WIRE FROM TERMINAL.
—HEAT STAYS ON, THERMOSTAT OK, CHECK HEATING SYSTEM.
—HEAT STOPS, HEATING SYSTEM OK, CHECK THERMOSTAT.
THERMOSTAT CHECKOUT:
• SET SYSTEM SWITCH TO HEAT OR AUTO.
• SPACE TEMPERATURE IS HIGHER THAN HEAT SETPOINT (IF
NOT, LOWER HEAT SETPOINT TO 5°F BELOW SPACE TEMPER-
TURE).
—HEAT TURNS OFF, THERMOSTAT AND HEATING SYSTEM OK.
—HEAT STILL ON, REPLACE THERMOSTAT.
•• HEAT TURNS OFF, THERMOSTAT AND HEATING SYSTEM OK.
•• HEAT ON, REPLACE Q7300.
CHECK COOLING SYSTEM:
• WAIT MINIMUM 4 MIN. OFF TIME.
• JUMPER RC (R IF HEAT PUMP) TO Y1 AT THERMOSTAT OR
EQUIPMENT TERMINAL STRIP.
—COOL OFF, THERMOSTAT OK, CHECK COOLING SYSTEM.
—COOL ON, COOLING SYSTEM OK, CHECK THERMOSTAT.
THERMOSTAT CHECKOUT:
• SET SYSTEM SWITCH TO COOL OR AUTO.
• SPACE TEMPERATURE IS HIGHER THAN COOL SETPOINT (IF
NOT, LOWER COOL SETPOINT TO 5°F BELOW SPACE TEMPER-
TURE).
—COOL COMES ON, THERMOSTAT AND COOLING SYSTEM OK.
—NO COOL, REPLACE THERMOSTAT.
•• COOL ON, THERMOSTAT AND COOLING SYSTEM OK.
•• COOL TURNS OFF, REPLACE Q7300.
CHECK COOLING SYSTEM:
• WAIT MINIMUM 2 MIN. ON TIME.
• REMOVE RC (R IF HEAT PUMP) WIRE FROM TERMINAL.
—COOL ON, THERMOSTAT OK, CHECK COOLING SYSTEM.
—COOL OFF, COOLING SYSTEM OK, CHECK THERMOSTAT.
THERMOSTAT CHECKOUT:
• SET SYSTEM SWITCH TO COOL OR AUTO.
• SPACE TEMPERATURE IS LOWER THAN COOL SETPOINT (IF
NOT, RAISE COOL SETPOINT TO 5°F ABOVE SPACE TEMPER-
TURE).
—COOL TURNS OFF, THERMOSTAT AND COOLING SYSTEM OK.
—COOL STILL ON, REPLACE THERMOSTAT.
•• COOL TURNS OFF, THERMOSTAT AND COOLING SYSTEM OK.
•• COOL ON, REPLACE Q7300.
46
ACTION
M4417