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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My issue is regarding a tcont900 thermostat
, the

Customer Question

Customer: **** ***. My issue is regarding a tcont900 thermostat
JA: Thanks. Can you give me any more details about your issue?
Customer: the thermostat went blank.
JA: OK got it. Last thing — JustAnswer charges a fee (generally around $18) to post your type of question to HVAC Experts (you only pay if satisfied). There are a couple customers ahead of you. We can help you for less if you're not in a rush. Are you willing to wait a bit?
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Submitted: 10 months ago.
Category: HVAC
Customer: replied 10 months ago.
The thermostat is connected to a trane comfort link II furnace. I checked the wires behind the thermostat and there is about 12V between 2 of the 3 wires.
Customer: replied 10 months ago.
Please text the response to ***-******* or email to ***.*.****@*****.***
Expert:  gotoman for ac replied 10 months ago.

Blank screen is usually blown fuse or bad transformer or float switch tripped. Are you using Air Conditioning or Heat. Do you have a heat pump or gas heat. Are you comfortable taking panel off unit. Russ

Customer: replied 10 months ago.
Did you read my message. There is power in the wire behind the thermostat. It is heat only furnace and I checked the fuse on the panel in furnace. The fuse is purple color and it is OK.
Expert:  gotoman for ac replied 10 months ago.

You need to get at least 24 volts between R and B before screen will work. 12 volts means something is open in the circuit. Check drain switch. Russ