Справочник Пользователя для Honeywell THM5421C1008

35

68-0287—1

Display does not come on

Thermostat is not being powered

Check if the thermostat is mounted and latched on the wall 

plate. If not:

— Mount and latch the thermostat on the wallplate.

Check if the circuit breaker is tripped or the fuse is blown; if 

it is:

— Reset the circuit Breaker or replace the fuse.

Check if the power switch at the equipment is in the off 

position; if it is:

— Set to the on position.

Check for 24 Vac between terminals 2 and 3 at the 

thermostat.

— Replace any broken wires if 24Vac is not present.

— Replace thermostat if 24Vas is present.

Check for 24 Vac between terminals R and C at the 

Equipment interface module.

— If 24Vac is not present consult electrician.

— If 24 Vac is Present replace Equipment interface 

module.

Temperature setting does not 

change

The upper and lower temperature 

limits reached

Check temperature setpoints.

Check installer setup Numbers 0600 and 610; modify as 

needed.

Keypad is fully locked

Check Installer Setup Number 670 to change keypad 

locked options.

Heating or cooling does not 

come on and thermostat is not 

calling for heat or cool.

Thermostat minimum off timer is 

activated

Wait up to 5 minutes for the system to respond (Wait is 

displayed on the Thermostat home screen.

System selection is not set to Heat 

or Cool

Set system selection to correct setting.

Heating or cooling does not 

come on and thermostat is 

calling for heat or cool.

Heating or cooling equipment is not 

operating

Check Wiring.

Check installer setup number 172 and verify the correct 

system type is chosen.

Verify operation of equipment in system test mode.

Heat does not turn on (“Heat On” 

is solid in the display)

Heating Equipment failure

Check for 24 Vac at the equipment on the secondary side 

of the transformer between power and common. If voltage 

is not present check the heating equipment to find the 

cause of the problem.

Check for 24 Vac between the heat terminal(s) on the 

equipment interface Module and transformer common. If 

present check heating equipment to find the cause of the 

problem.

Loose or broken wire connection 

between Equipment Interface 

Module and heating equipment.

Check for 24 Vac between the heat terminal(s) on the 

HVAC equipment and system transformer common. If 

voltage is not present check for loose or broken wires 

between the EIM and heating equipment.

Communication is not being 

completed

End the call for heat at the thermostat then repeat the call 

for heat. Check the communication LED on the EIM board.

— If the LED does not blink, check communication 

wiring (wire between terminal 1 on both the EIM 

and thermostat.

— If the LED does blinks correctly, check for 24 Vac 

between heating terminals on the EIM and the sys-

tem common.

If 24 Vac is not present check the R to Rh connection on 

the EIM, if the connection is good replace the EIM.