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Category: HVAC
Satisfied Customers: 13391
Experience:  15yrs in the HVAC industry with certificates and degrees.
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I have a honeywell T8400C thermostat that loses the display

Customer Question

i have a honeywell T8400C thermostat that loses the display periodically. If i turn the breaker to the furnace off and then back on the display comes back and the AC works fine.
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: thermostat i think
JA: Do you plan on doing the work yourself?
Customer: yes if it's just the themostat
JA: Anything else we should know to help you best?
Customer: no
Submitted: 2 months ago.
Category: HVAC
Expert:  HVAC Guru replied 2 months ago.

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Either the thermostat is bad or you could have a wiring issue the thermostat itself. If you are hard resetting it you should really check with a volt meter for 24 volts from R to C at the thermostat to see if you have power there when it is blank. If not you may want to check the wiring to the board in the furnace and transformer to make sure they are not causing a loss of power to the thermostat head. If the thermostat does have power and is blank just replace the thermostat.

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