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Hello: In a recent visit from my HVAC serviceman, I complained about a buzzing sound coming from the electrical junction box that is installed with a transformer/relay inside of it, before entering the inside fan unit. The crewman recommended replacing the Transformer/Relay and put forth a $420.00 proposal. Looking into the transformer cost (MARS - HF94F-10A 120-1 99291 @ $11.25), I cannot justify $400.00 to remove and replace a $11.00 transformer that would take 10 minutes. I have attached a file with the noise. has anyone experienced this and is the diagnosis correct? Please advise. Thank you.
@farhadR what was the original failure mode? When the thermostat called for heat would the furnace go through the entire cycle and start the burners but the blower fan would not turn on?
Thank you for your response, Scott. The sound starts only when the thermostat calls for heat and there are no failures in delivering heat or any components of the system. Only there is this buzzing sound coming from the junction box that the transformer/relay is located. Based on my little knowledge and small research, buzzing sounds are caused by the expansion of the core metal lamination or the magnetic field produced when electricity flows through the transformer’s coils, which is understandable. The buzzing sound I am referring to seems to be a bit loud and unusual and wanted to know if this was a normal sound or abnormal and would replacing such component, remove or at least reduce the sound. Please advise. Thank you.
@farhadR Honestly I don't have much experience with the transformer but if I were in your shoes I would try to get a direct replacement from Amazon and do a quick swap to see if that solves the issue. Let me know if the transformer was the issue once you do the swap.
Great. Thank you. Will post the results.
