Heating, Air Conditioning, Fridge, HVAC/tripped 3.2amp transformer CB


Hi, the built-in CB on the furnace transformer will pop in Cool mode only after about 5 seconds of operation.  It does not trip in FAN or Heat Modes.  I recently replaced the reversing valve solenoid and, after about a month, this one is now showing signs of excessive heat in the coils and was hot to the touch.  I checked the voltage to the reversing valve coil and it was 29.8V, not 24V.  Has the furnace transformer gone bad with over-voltage or is it something else?


Your transformer should be a 40 VA rated or a little higher for starters. You can check voltage at your defrost board should have 24 volts ac. Check your secondary side of the transformer ( remove all low voltage wires from the low side of the transformer )then check for 24 voltac ,if not 24 volts consider replacing the transformer. Transformers are minimal cost items, Typically a furnace is 120 volt Check to make sure that your incoming voltage feeding the transformer is a few volts of 120.If it's way low or way higher than 120 that would cause the secondary side to be more or less than the ideal 24 volt ac.Check the voltage at your t-stat with nothing calling you should have 24 volts ac at R to G R to Y  R to W and if you have a Common on the stat R to C .Your low voltage wires need to be 18 gauge copper. That is the recommended size. All your 24 volt terminal connections should be tight everywhere, at the furnace and outdoor unit and t-stat and any wire nut connections and relays. Remove the defrost board and look at the back side for any burn marks that may indicate overheating of resisters,typically when your calling for cooling the first stage of cool energises the reversing valve coil, 2nd stage energises the compressor contactor and blower fan.You should not have power to the RV coil when nothing is calling.It would not be unusal for the RV coil to be warm or even hot if it has been energised for a long period of time.

Heating, Air Conditioning, Fridge, HVAC

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40+ years diversified experience.An HVAC/Refrigeration Self Employed Contractor since 1986. NATE Certifield. Answer questions pertaining to Residential and Commercial Air Conditioning , Warm Air Heating, Heat Pump systems.Mechanical and Electrical troubleshooting of these systems.Be as detailed as possible when describing problem.Packaged unit or split systems.No appliance questions.


Installation and Troubleshooting, Mechanical and Electrical, in following areas, Refrigeration ( Walk In and Reach In Coolers and Freezers ) Commercial Roof Top and Packaged Heating/Cooling ( Natural Gas,Propane, Electric, and Heat Pumps ) Computer Room Air Conditoning Systems,Commercial Residential Packaged and Split Systems Air Conditoning and Heat Pumps.Warm Air Oil , Natural and Propane Gas Heating systems.

Graduated from Private Technical School in 1975. An HVAC/Refrigeration Contractor . Have Unlimited Heating/Piping and Cooling Contractor License.Limited Sheetmetal Contractors License.NATE Certifield. York Certifield Master Heat Pump Technician 1986. Served 33 years combination Active Duty Air Force , Air Force Reserves and Air National Guard in the HVAC/Refrigeration Shop/Mechanical Shop. Troubleshooting/Installing HVAC/Refrigeration Equiptment Worldwide. Retiring in 2003 as a Senior NCO ,and a Mechanical Superintendent.

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