Troubleshooting Defrost Fault Code on a Heat Pump

In this video we go out to a new customer's home to troubleshoot a heat pump for a no heat service call. The outdoor defrost board on this Nortek heat pump was showing a fault code of 04, which is an issue with the outdoor coil temperature sensor. This is a demand defrost system so it uses a defrost board with a termination set point, along with an outdoor coil temperature sensor, and an outdoor ambient temperature sensor. I performed an ohms test on the OAT and OCT thermistors/sensors. The OCT thermistor was out of range based on the temperature it was outside at the time of testing. I was reading just over 34k ohms and should have been reading 19k ohms. It was 51.5 degrees outside when I tested the sensor, but based on the ohm reading the sensor that it was 30 degrees outside. The diagnostic fault codes on that board make it pretty easy to troubleshoot these units, which is a nice feature. Customer ended up opting to replace the board, OCT, and OAT sensors because he didn't want me having to come back out there again in a couple of months for a failed defrost board or a bad OAT sensor. I can't say that I disagree with that thinking based on how far out they live. Luckily the board on this one isn't an expensive part, so it didn't cost much more to swap it all out. The original OCT sensor was mounted in the same orientation that I showed in the video after swapping it out. You could see it earlier in the video how it was mounted from the factory. I didn't like the orientation of it, so before popping the top back on, I flipped it around to hopefully help keep the elements out of sensor better. My name is Jake Porter and I am the sole owner & operator of Magnolia Services, LLC. I am a residential HVAC contractor based out of Johnson City, TN. My service area includes: Johnson City, Jonesborough, Unicoi, Erwin, Elizabethton, Hampton, Boones Creek, Gray, Limestone, Lamar, Telford, Watauga, Chuckey, Piney Flats, Bluff City, Blountville, and parts of Kingsport. If you are in my service area and in need of HVAC services, please do not hesitate to contact me at 423-483-7158. Please do not contact me for DIY technical support. Unfortunately, I would need to be able to put my own tools and hands on the equipment in order to assist you. Thanks for watching. Stay safe & best wishes. #hvac #hvacrepair #defrost #defrostboard #octsensor #oatsensor #heatingrepair #heatpumprepair #heatpumps #heatpump #magnoliaservices #magnoliaservicestn #jakeporterhvac #heatingrepair #heatingandcooling #heat #tennessee