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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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MY Carrier system thermostat says Fault Code 178 Indoor Unit

Customer Question

MY Carrier system thermostat says Fault Code 178 Indoor Unit Communication what does that mean
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: System is not working
JA: Do you plan on doing the work yourself?
Customer: If simple
JA: Anything else we should know to help you best?
Customer: System is less than 2 years old and is service twice a year
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello, Code 178, Indoor Units printed circuit board, or 24 volt control circuit is non functional.. it could be a bad thermostat, printed circuit board, or just an oxidized wire connection. Trouble shooting that is difficult. Many if not most HVAC technicians will resort to inspecting those components for burn marks or bad connections and replace the most suspect piece or pieces and hope for the best.

Tell me a lot about your technical skills in electronics so that I can coach you most effectively, or if none of this is in your bag of skills, tell me which direction you are from the center of the nearest city so I can look for a well rated company that has skill sets in range.

We can go from there